SQL update & insert - php

Question

I have a MYSQL table named issues_tot including following columns:
v_code, oid, amount, mod_date
02) Then I need to update or insert records of the table according to the given condition as follows:
if(($vt == $vote)||($of == $ono)){
03) update is working properly, but insert is not (else part). My code is showing below:
if (isset($_POST["submit"]))
{
$ono =$_POST["oid"];
$amt =$_POST["amt"];
$allo=mysql_fetch_array(mysql_query("SELECT * FROM allocation WHERE al_code='{$_GET['al_code']}'"));
$vote=$allo['v_code'];
$current_date = date("Y-m-d H:i:s");
$query ="select * from issues_tot where v_code='$vote' ";
$result = mysql_query($query) or die ( mysql_error());
$row = mysql_fetch_assoc($result);
$vt = $row['v_code'] ;
$of = $row['oid'] ;
if(($vt == $vote)||($of == $ono)){
$query ="UPDATE issues_tot SET oid = $ono, amount = amount + $amt WHERE v_code=$vote";
$result = mysql_query($query) or die ( mysql_error());
$rc = mysql_affected_rows();
}else {
$query ="INSERT INTO issues_tot (v_code, oid, amount, mod_date) VALUES ('$vote', '$ono', '$amt', '$current_date')";
$result = mysql_query($query) or die ( mysql_error());
$rc = mysql_affected_rows();
}
}
I can not understand what I am going wrong. Can anyone help me ?. Pls