Did you use $GET or $POST ?
Suppose you send the varible " name " with the POST method, you'll get it with $POST["name"]
If you send it with GET, $GET["name"]
If you use a version of PHP < 4.1.0, $POST and $GET, you can use $HTTP_POST_VARS (ex: $HTTP_POST_VARS["name"]) or $HTTP_GET_VARS
Of course, be sure that "track_vars" in your configuration file is enabled.