Php nuke admin page error?

[Nick]

ok, i have everything working fine im about to create my super admin and when i click create it should bring me to my admin page, but it says access denied!! it was working fine with 8.1 but i downgraded to 7.8! Heres the part i changed is there anything wrong?:

<?php

/************************************************************************/
/* PHP-NUKE: Web Portal System */
/* =========================== */
/* */
/* Copyright (c) 2005 by Francisco Burzi */
/* http://phpnuke.org */
/* */
/* This program is free software. You can redistribute it and/or modify */
/* it under the terms of the GNU General Public License as published by */
/* the Free Software Foundation; either version 2 of the License. */
/************************************************************************/

define('ADMIN_FILE', true);
if($aid AND (!isset($admin) OR empty($admin)) AND $op!='login') {
unset($aid);
unset($admin);
echo "Access denied";
die();
}
// Uncomment the following block of code after editing the next line to match your site domain
$domainname = "www.Sector-7Gaming.net";
if ($_SERVER['SERVER_NAME'] != $domainname ) {
echo "Access denied";
die();
}