Cannot Modify Header Iformation - php

Question

I am getting this error:
Warning: Cannot modify header information - headers already sent by (output started at /home/renta142/public_html/includes/connection_prop.php:14) in /home/renta142/public_html/login.php on line 31
My PHP Code is:
<?php
session_start();
if($_SESSION['user']['id']!=""){
header("location:index.php");
exit();
}
$login_email=$_POST[email];
$username=$_POST[username1];
$name=$_POST[name];
$er=$_POST[er];
if(trim($_POST["SignIn"])=="Sign In"){
include("includes/connection_user.php");
$user_=$_POST["username"];
$pass=$_POST["pass"];
$query=mysql_query("select * from user_registration where UserID='".$user_."' and Password='".$pass."' and Display='1'");
$result=mysql_fetch_array($query);
if(!strcmp($result[Password],$pass)){
$_SESSION['user']['id'] = $result[AID];
$_SESSION['user']['password'] = $result[Password];
$_SESSION['user']['username'] = $result[UserID];
$_SESSION['user']['name']=$result[Name];
$ref=$_SESSION["refer_url"];
if($_REQUEST['ref']=="sell"){
header("Location:postproperty_sell.php");
exit();
}
else if($ref==""){
header("Location:postproperty.php");
exit();
}
else{
header("Location:$ref");
exit();
}
}else{
$errsg="Invalid Username and Password !";
}
mysql_close();
}
include("config.php");
$sitename=ucfirst($thirdsite)." - Property in ".ucfirst($addresscity);
$keys="property in ".ucfirst($addresscity);
$desc="Real estate agents offers - property in ".ucfirst($addresscity);
include("includes/header.php");
include("includes/left.php");
?>
<script language='javascript' src="images/script.js"></script>
<script type="text/javascript">
function popUp_file(URL){
day = new Date();
id = day.getTime();
eval("page" + id + " = window.open(URL, '" + id + "', 'toolbar=0,scrollbars=1,location=1,statusbar=0,menubar=0,resizable=0,width=900,height=600');");
}
<?php if($_REQUEST[fcode]=='wrong'){?>
window.onload=function(){document.getElementById('fpass').style.display='block';}
<?php }?>
<!--
function MM_openBrWindow(theURL,winName,features) { //v2.0
window.open(theURL,winName,features);
}
//-->
</script>
<td valign="top" align="center" colspan="2">
<table width="794" border="0" cellspacing="0" cellpadding="0">
<tr>
<td><table width="100%" border="0" cellspacing="0" cellpadding="0">
<tr>
<td width="1%" align="right" valign="bottom"><img src="images/11.jpg" width="10" height="10" alt="" /></td>
<td width="97%" style="background:url(images/12.jpg) repeat-x bottom;"> </td>
<td width="2%" align="left" valign="bottom"><img src="images/13.jpg" width="10" height="10" alt="" /></td>
</tr>
<tr>
<td style="background:url(images/21.jpg) repeat-y right;"> </td>
<td><table width="100%" border="0" cellspacing="0" cellpadding="0">
<tr>
<td align="left" class="green"> </td>
<td> </td>
</tr>
<tr>
<td align="left" valign="middle" class="green"><table width="100%" border="0" cellpadding="0" cellspacing="0">
<tr>
<td width="5%"><img src="images/customer_login.gif" alt="CUSTOMER LOGIN" width="24" height="23" /></td>
<td width="92%">PROPERTY OWNER LOGIN </td>
</tr>
</table></td>
<td align="left" class="green"><table width="100%" border="0" cellpadding="00" cellspacing="0">
<tr>
<td width="5%"><img src="images/mbenifites.gif" alt="MEMBERSHIP BENEFITS" width="16" height="17" /></td>
<td width="92%"> FREE MEMBERSHIP BENEFITS</td>
</tr>
</table></td>
</tr>
<tr>
<td valign="top"> </td>
<td valign="top"> </td>
</tr>
<tr>
<td width="50%" valign="top"><?php if($errsg){ echo "<br /><div class='alert' align='center'>".$errsg."</div><br />"; } ?>
<table width="100%" cellpadding="4" cellspacing="1" class="heading" valign="top">
<form action="login.php?ref=<?php echo $_REQUEST['ref']; ?>" method="post" name="signin" id="signin" onsubmit="return loginform();">
<tr>
<td class="txt">Username<font color="red">*</font></td>
<td width="1" align="left"><strong>:</strong></td>
<td align="left"><input name="username" type="text" id="username" onfocus="if(this.value=='Username') this.value='';" onblur="if(this.value=='') this.value='Username';" value="Username" /></td>
</tr>
<tr>
<td class="txt">Password<font color="red">*</font></td>
<td align="left"><strong>:</strong></td>
<td align="left"><input type="password" name="pass" onfocus="if(this.value=='**********') this.value='';" onblur="if(this.value=='') this.value='**********'" value="**********" /></td>
</tr>
<tr>
<td> </td>
<td align="left"> </td>
<td align="left"><input type="submit" name="SignIn" value="Sign In" class="button" /></td>
</tr>
<tr>
<td> </td>
<td> </td>
<td align="left"><font color="#333333" size="2" face="Arial, Helvetica, sans-serif"> <img src="images/nuser.gif" alt="New User registration" width="19" height="21" alt="" /> New User ?</font><a href="login.php#reg"><font color="#0000FF" size="2" face="Arial, Helvetica, sans-serif">Register First</font><br />
</a> <font color="#0000FF" size="2" face="Arial, Helvetica, sans-serif">Forgot Password </font></td>
</tr>
</form>
</table></td>
<td width="50%" valign="top" style="background:url(images/login_page.jpg) no-repeat right; height:200px;"><table width="100%" border="0" cellspacing="0" cellpadding="0">
<tr>
<td align="left" valign="top"><table width="100%" border="0" cellspacing="2" cellpadding="2">
<tr>
<td width="11%" align="center" valign="top" style="padding-top:8px;"><img src="images/bullet-cir1.jpg" width="8" height="8" alt="" /></td>
<td width="89%" valign="top"><font size="2" face="Arial, Helvetica, sans-serif">Advertise your properties for Sale/Rent/PG </font></td>
</tr>
<tr>
<td align="center" valign="top" style="padding-top:8px;"><img src="images/bullet-cir1.jpg" width="8" height="8" alt="" /></td>
<td valign="top"><font size="2" face="Arial, Helvetica, sans-serif">Get Special offers and freebies</font></td>
</tr>
<tr>
<td align="center" valign="top" style="padding-top:8px;"><img src="images/bullet-cir1.jpg" width="8" height="8" alt="" /></td>
<td valign="top"><font size="2" face="Arial, Helvetica, sans-serif">Get updates on our new products</font></td>
</tr>
<tr>
<td align="center" valign="top" style="padding-top:8px;"><img src="images/bullet-cir1.jpg" width="8" height="8" alt="" /></td>
<td valign="top"><font size="2" face="Arial, Helvetica, sans-serif">Response through mail, phone</font></td>
</tr>
</table> </td>
</tr>
</table></td></tr>
<tr>
<td colspan="2"> </td>
</tr>
<tr>
<td colspan="2" ><table width="100%" border="0" align="center" cellpadding="0" cellspacing="0" style="border:#3399FF 1px solid;">
<tr>
<td align="left" bgcolor="#E1F1F4" style="padding-left:3px; padding-right:3px;"> <strong><font size="2" face="Arial, Helvetica, sans-serif"><img src="images/note.gif" alt="<?php echo $thirdsite ?>is commited your information is strictly confidential, unless you want to expose it." width="19" height="18" /> Note:</font></strong></td>
</tr>
<tr>
<td align="center" bgcolor="#E1F1F4" style="padding-left:3px; padding-right:3px;"><div align="justify" style="padding-left:3px; padding-right:3px;"><font color="#666666" size="2" face="Arial, Helvetica, sans-serif"> <?php echo ucfirst($thirdsite); ?> is commited your information is strictly confidential, unless you want to expose it.</font></div></td>
</tr>
<tr>
<td align="center" bgcolor="#E1F1F4"> </td>
</tr>
</table></td>
</tr>
<tr>
<td colspan="2"> </td>
</tr>
</table></td>
<td style="background:url(images/22.jpg) repeat-y left;"> </td>
</tr>
<tr>
<td align="right" valign="top"><img src="images/31.jpg" width="10" height="10" alt="" /></td>
<td style="background:url(images/32.jpg) repeat-x top;"> </td>
<td align="left" valign="top"><img src="images/33.jpg" width="10" height="10" alt="" /></td>
</tr>
</table></td>
</tr>
<tr>
<td></td>
</tr>
</table>
<a name="fp"></a>
<div id="fpass" style="display:none;">
<table width="794" border="0" align="center" cellpadding="0" cellspacing="0">
<tr>
<td><table width="100%" border="0" cellspacing="0" cellpadding="0">
<tr>
<td width="1%" align="right" valign="bottom"><img src="images/11.jpg" width="10" height="10" alt="" /></td>
<td width="97%" style="background:url(images/12.jpg) repeat-x bottom;"> </td>
<td width="2%" align="left" valign="bottom"><img src="images/13.jpg" width="10" height="10" alt="" /></td>
</tr>
<tr>
<td style="background:url(images/21.jpg) repeat-y right;"> </td>
<td align="left"> </td>
<td style="background:url(images/22.jpg) repeat-y left;"> </td>
</tr>
<tr>
<td style="background:url(images/21.jpg) repeat-y right;"> </td>
<td align="left"><table width="100%" border="0" cellpadding="00" cellspacing="0">
<tr>
<td width="3%"><span class="green"><img src="images/forget_pass.gif" alt="FORGOT PASSWORD" width="20" height="19" /></span></td>
<td width="97%"><span class="green"> FORGOT PASSWORD</span></td>
</tr>
</table></td>
<td style="background:url(images/22.jpg) repeat-y left;"> </td>
</tr>
<tr>
<td style="background:url(images/21.jpg) repeat-y right;"> </td>
<td><table width="100%" border="0" align="right" cellpadding="2" cellspacing="0">
<form action="forget_password_submit.php" method="post" name="forget_password" id="forget_password">
<input type="hidden" name="chk" value="2" />
<?php if($_GET[fcode]) echo ' <tr>
<td class="alert" align="center" colspan="3">Your EmailID or UserName Is Not Found In Our Database, Please Try Again!!!</td></tr>';?>
<tr >
<td width="20%" align="right" valign="top" class="txt"> Username</td>
<td width="2%" valign="top"><b>:</b></td>
<td width="78%" align="left" valign="top"><input type="text" name="username1" /></td>
</tr>
<tr>
<td colspan="2" align="right" class="heading"> OR</td>
<td class="heading" align="left"> </td>
</tr>
<tr>
<td align="right" valign="top" class="txt"> Email-ID</td>
<td valign="top"><b>:</b></td>
<td align="left" valign="top"><input type="text" name="email1" /></td>
</tr>
<tr>
<td colspan="3" align="right" height="8"></td>
</tr>
<tr>
<td align="right"> </td>
<td align="center"> </td>
<td align="left"><input name="submit" type="submit" onclick="return ForgetpassForm();" value="Submit" class="button" /></td>
</tr>
<tr>
<td align="right"> </td>
<td align="right"> </td>
<td align="left"><font color="#333333" size="2" face="Arial, Helvetica, sans-serif"><img src="images/login.gif" alt="Existin user login" width="19" height="21" /></font> <font color="#0000FF" size="2" face="Arial, Helvetica, sans-serif"><strong>Login</strong></font></td>
</tr>
<tr>
<td align="right" colspan="4" height="8"></td>
</tr>
<tr>
<td colspan="3" align="right"><table width="100%" border="0" align="center" cellpadding="0" cellspacing="0" style="border:#3399FF 1px solid;">
<tr>
<td align="left" bgcolor="#E1F1F4" style="padding-left:3px; padding-right:3px;"> <strong><font size="2" face="Arial, Helvetica, sans-serif"><img src="images/note.gif" alt="Enter Your UserName or Email-ID which you had entered in registration form and get your password through eMail." width="19" height="18" /></font></strong><strong><font size="2" face="Arial, Helvetica, sans-serif"> Note:</font></strong></td>
</tr>
<tr>
<td align="center" bgcolor="#E1F1F4" style="padding-left:3px; padding-right:3px;"><div align="justify" style="padding-left:3px; padding-right:3px;"><span class="text"> Enter Your UserName or Email-ID which you had entered in registration form and get your password through eMail. </span></div></td>
</tr>
<tr>
<td align="center" bgcolor="#E1F1F4"> </td>
</tr>
</table></td>
</tr>
<tr>
<td colspan="3" align="center" height="7"></td>
</tr>
</form>
</table></td>
<td style="background:url(images/22.jpg) repeat-y left;"> </td>
</tr>
<tr>
<td align="right" valign="top"><img src="images/31.jpg" width="10" height="10" alt="" /></td>
<td style="background:url(images/32.jpg) repeat-x top;"> </td>
<td align="left" valign="top"><img src="images/33.jpg" width="10" height="10" alt="" /></td>
</tr>
</table></td>
</tr>
</table>
</div>
<?php //if($errsg=="Invalid Username and Password !"){?>
<a name="reg"></a>
<table width="794" border="0" align="center" cellpadding="0" cellspacing="0">
<tr>
<td><table width="100%" border="0" cellspacing="0" cellpadding="0">
<tr>
<td width="1%" align="right" valign="bottom"><img src="images/11.jpg" width="10" height="10" alt="" /></td>
<td width="97%" style="background:url(images/12.jpg) repeat-x bottom;"> </td>
<td width="2%" align="left" valign="bottom"><img src="images/13.jpg" width="10" height="10" alt="" /></td>
</tr>
<tr>
<td style="background:url(images/21.jpg) repeat-y right;"> </td>
<td align="left"> </td>
<td style="background:url(images/22.jpg) repeat-y left;"> </td>
</tr>
<tr>
<td style="background:url(images/21.jpg) repeat-y right;"> </td>
<td align="left" class="heading"><table width="100%" border="0" cellpadding="00" cellspacing="0">
<tr>
<td width="3%"><img src="images/if_you_do.gif" alt="If you do not have an existing Customer Account with us fill in the form below" width="19" height="19" /></td>
<td width="97%"> If you do not have an existing User Account with us fill in the form below. </td>
</tr>
</table></td>
<td style="background:url(images/22.jpg) repeat-y left;"> </td>
</tr>
<tr>
<td style="background:url(images/21.jpg) repeat-y right;"> </td>
<td align="left"> </td>
<td style="background:url(images/22.jpg) repeat-y left;"> </td>
</tr>
<tr>
<td align="right" valign="top"><img src="images/31.jpg" width="10" height="10" alt="" /></td>
<td style="background:url(images/32.jpg) repeat-x top;"> </td>
<td align="left" valign="top"><img src="images/33.jpg" width="10" height="10" alt="" /></td>
</tr>
</table></td>
</tr>
</table>
<table width="794" border="0" align="center" cellpadding="0" cellspacing="0">
<tr>
<td><table width="100%" border="0" cellspacing="0" cellpadding="0">
<tr>
<td width="1%" align="right" valign="bottom"><img src="images/11.jpg" width="10" height="10" alt="" /></td>
<td width="97%" style="background:url(images/12.jpg) repeat-x bottom;"> </td>
<td width="2%" align="left" valign="bottom"><img src="images/13.jpg" width="10" height="10" alt="" /></td>
</tr>
<tr>
<td style="background:url(images/21.jpg) repeat-y right;"> </td>
<td align="left" class="green"><table width="100%" border="0" cellpadding="00" cellspacing="0">
<tr>
<td width="5%"><img src="images/NEW-USER-REGISTER-FORM.gif" alt="NEW USER REGISTER FORM " width="26" height="27" /></td>
<td width="97%"> NEW USER REGISTER FORM </td>
</tr>
</table></td>
<td style="background:url(images/22.jpg) repeat-y left;"> </td>
</tr>
<tr>
<td style="background:url(images/21.jpg) repeat-y right;"> </td>
<td align="left"> </td>
<td style="background:url(images/22.jpg) repeat-y left;"> </td>
</tr>
<tr>
<td style="background:url(images/21.jpg) repeat-y right;"> </td>
<td align="left"><form name="register" method="POST" action="registration_submit.php?ref=<?php echo $_REQUEST['ref']; ?>" onsubmit="return registerForm();">
<table width="100%" border="0" cellspacing="0" cellpadding="0">
<tr>
<td width="50%" valign="top" style="border:#CCCCCC 1px solid;">
<table width="100%" cellpadding="4" cellspacing="0">
<tr>
<td bgcolor="#EEEEEE"><font size="2" face="Arial, Helvetica, sans-serif">User Login Information</font></td>
<td bgcolor="#EEEEEE"> </td>
<td align="right" bgcolor="#EEEEEE"><span class="alert">* Mandatory Fields</span></td>
</tr>
<tr>
<td width="39%" class="tdspace txt"><font color="red">*</font>Username</td>
<td width="3%">:</td>
<td width="58%"><input name="username" type="text" id="username" size="25" /></td>
</tr>
<tr>
<td class="tdspace txt"><font color="red">*</font>Password</td>
<td>:</td>
<td><input type="password" name="password" size="25" /></td>
</tr>
<tr>
<td class="tdspace txt"><font color="red">*</font>Confirm Password</td>
<td>:</td>
<td><input type="password" name="rpassword" size="25" /></td>
</tr>
<tr>
<td class="tdspace txt"><font color="red">*</font>Email-ID</td>
<td>:</td>
<td><input type="text" name="email" size="25" /></td>
</tr>
<tr>
<td colspan="3" bgcolor="#EEEEEE"><font size="2" face="Arial, Helvetica, sans-serif">Contact Information</font></td>
</tr>
<tr>
<td class="tdspace txt"><font color="red">*</font>Name</td>
<td>:</td>
<td><input type="text" name="name" size="25" /></td>
</tr>
<tr>
<td class="tdspace txt"><font color="red">*</font>Verification Code</td>
<td>:</td>
<td><input name="verify_code" type="text" size="15" />
<img src="verificationimage.php" alt="verification image, type it in the box" width="60" height="30" align="absbottom"/></td>
</tr>
<tr>
<td colspan="3" class="text"><input type="checkbox" name="term" />
I have read <font color="red">Terms and Conditions</font> and I accept these conditions.</td>
</tr>
<tr>
<td align="center"> </td>
<td align="center"> </td>
<td align="left"><input name="submit2" type="submit" value="Submit" class="button" />
<input name="reset" type="reset" value="Reset" class="button" />
<input name="flg" type="hidden" id="flg" value="1" /></td>
</tr>
</table></td>
<td width="1%" > </td>
<td width="49%" valign="top"><img src="images/register.jpg" alt="For Free registration on <?php echo ucfirst($thirdsite); ?>, Advertise your properties for Sale/Rent/PG, Get Special offers and freebies, Get updates on our new products, Response through mail, phone" width="380" height="380" /></td>
</tr>
</table>
</form></td>
<td style="background:url(images/22.jpg) repeat-y left;"> </td>
</tr>
<tr>
<td align="right" valign="top"><img src="images/31.jpg" width="10" height="10" alt="" /></td>
<td style="background:url(images/32.jpg) repeat-x top;"> </td>
<td align="left" valign="top"><img src="images/33.jpg" width="10" height="10" alt="" /></td>
</tr>
</table></td>
</tr>
</table>
<?php //}?>
</td>
<script language='javascript'>signin.username.focus();</script>
<?php
//include("includes/right.php");
include("includes/footer.php");
?>

Answer 1

public_html/includes/connection_prop.php:14 is probably outputting some blank spaces. Check that file and other includes for whitespace around tags.
You cannot send headers if any text has already been output