If PHP is not outputting anything or if you think any error infomation should be displayed, but is not then it might be that your display_errors setting may be turned off.

If you have access to php.ini, then locate the entry:

and make sure it is set to On

In case you don't have access to the php.ini file, you can write the following code on the first line of php file:

<?php ini_set('display_errors', '1'); ?>

If you are still not getting any output, you may also add the following line, just below the above code:

error_reporting(E_ALL);