problem in get $vbulletin into external class

[manuel.fho]

This works

PHP Code:

<?php
chdir('/home/x/public_html/forum/');
require_once('./global.php');
return $vbulletin->userinfo;

This Dont Work D:

PHP Code:

<?php
class myCMS{
    function getVBInfo(){
        chdir('/home/x/public_html/forum/');
        require_once('./global.php');
        return $vbulletin->userinfo;
    }
}

$test = new myCMS();
print_r($test->getVBInfo());

Help in third party portal please.