If you have access to the php.ini, check to make sure your register globals is on. If not, then use $_GET or $HTTP_GET_VARS to strip off the user defined variables.
(I assume by "not working", you mean, you are getting some error about a your site variable not being defined or something likw that)
Correct me if I am wrong:
Jacob
(My bad Hearn, I just got what he was saying)
At any rate, you can refer to my post for the potential second half of a problem you can avoid ;-)