Sounds like a php error on the page.
Add the following code to line 1 of the page:
<?php
error_reporting(E_ALL);
ini_set('display_errors');
?>
be careful not to copy any surrounding spaces or create blank lines between code block when pasting the code or you will create other errors.
Post back with any errors that show on the page and a copy of your page in a zip archive so i can examine the code.