PHP Facebook App Problem

[blanky]

I am working on my second Facebook App and seem to have run into a problem. On my first App, I used \[code\]$user_id = $facebook->require_login();\[/code\]to get the ID of the user that was using my app. It worked great, and still does. However, on my second App, I used the same thing but keep getting the old 500 Internal Server Error. ( Using Opera as browser ) Not sure why, since the exact same code works on the other App. Here it is:\[code\]<?phprequire_once('facebook.php');$appapikey = 'APIKEYHERE';$appsecret = 'SECRETKEYHERE';$facebook = new Facebook($appapikey, $appsecret);$user_id = $facebook->require_login();echo $user_id;echo "Hello!";?>\[/code\]I have checked the server and PHP logs, none of them report any errors.