Ok, this one was fixed. For those who experienced the same problem :
1) Turn on php error output by adding
php_value display_errors 1
to .htaccess of the site
2) If you see a error message like this :
Fatal error: Uncaught exception 'Exception' with message 'Facebook needs the CURL PHP extension.' in /www/apps/fragaochsvara/app/qa-plugin/facebook-login/base_facebook.php:19 Stack trace:
Install CURL PHP and restart apache server.
This should solve the problem. At list it did for me