phpbb login hack

[discorevilo 0]

guys i read and did http://www.phpbb.com/kb/article.php?article_id=143 and got my script to have the loged in and login bit right... i had to make a new common.php and other bits removing all the templates bits to get it to work, it does but now when i try to use downloads.php?cat=catname the $cat doent work at all its completely ignored and so it doesnt include the page for that catogory and so the downloads script doesnt work.. can someone help me?