You can turn on your PHP errors with error_reporting:
error_reporting(E_ALL);
ini_set('display_errors', 'on');
Edit: It's possible that even after putting this, errors still don't show up. This can be caused if there is a fatal error in the script. From PHP Runtime Configuration:
Although display_errors may be set at runtime (with ini_set()), it won't have any affect if the script has fatal errors. This is because the desired runtime action does not get executed.
You should set display_errors = 1 in your php.ini file and restart the server.