Form submitting creating an 500 error - php

Question

I am trying to make this form work. But when I click submit it goes to at 500 internal server error.
Am I doing something wrong here or am I way off?
I've tried everything that was obvious changed post action even tried changing the submit button action.
This is my script for the form action.
<?php
$host="localhost"; // Host name
$username="signup"; // Mysql username
$password="pass"; // Mysql password
$db_name="signup"; // Database name
$tbl_name="signup_mysql"; // Table name
// Connect to server and select database.
mysql_connect("$host", "$username", "$password")or die("cannot connect");
mysql_select_db("$db_name")or die("cannot select DB");
// Get values from form
$venue_name=$_POST['venue_name'];
$production_company_name=$_POST['production_company_name'];
$venue_contact_name=$_POST['venue_contact_name'];
$location=$_POST['location'];
$office_location=$_POST['office_location'];
$capacity=$_POST['capacity'];
$age=$_POST['age'];
$description=$_POST['description'];
$facebook=$_POST['facebook'];
$twitter=$_POST['twitter'];
$soundcloud=$_POST['soundcloud'];
$website=$_POST['website'];
// Insert data into mysql
$sql="INSERT INTO $tbl_name(venue_name, production_company_name, venue_contact_name, email, location, office_location, capacity, age, description, facebook, twitter, soundcloud, website)VALUES('$venue_name', '$production_company_name', '$venue_contact_name', '$email', '$location', '$office_location', '$capacity', '$age', '$description', '$facebook', '$twitter', '$soundcloud', '$website')";
$result=mysql_query($sql);
// if successfully insert data into database, displays message "Successful".
if($result){
echo "Successful";
echo "<BR>";
echo "<a href='index.html'>Back to main page</a>";
}
else {
echo "ERROR";
}
?>
<?php
// close connection
mysql_close();
?>