standart variabels melfunction

Hi all, I have a problem with my settings of Apache and PHP i think.. When i call for example ($PHP_SELF) instead of ($_SERVER[PHP_SELF]) i get no output, just like when i call the url www.servername.tld/test.php?mode=test And i want to call the mode like this: print($mode); I just get a empty string. But when i call: print($_GET[mode]); I get the real output... I tried to walk troug the hole php.ini & the httpd.conf file, but nothing came up, so i relly hope that you can help me out here...! Sorry if it's a little off topic.. And THANKS A LOT!! Regards Martin Allan Jensen