What do you see when you attempt to preview this page? Normally if a php page has an error on it the page will display the error or a blank white page. If you are getting a white page you should put this code in at the top of your page in code view:
<?php
error_reporting(E_ALL);
ini_set('display_errors','on');
?>
Then save and test the page. If there are php errors on the page it should let you know what the problem is, please post back with what you get.