vBulletin session problem!

[kawe]

is it possible to create my own $_SESSION variable and use it on my custom PHP pages?

i already includes GLOBAL.PHP thru
require_once('global.php');
and create this line below
$vbulletin->session->set('uname', '123');
but when i fetch the variables, it doesn't shows.
echo '$vbulletin->session->vars[uname]:'.$vbulletin->session->vars['uname'];
doesn't work

do anyone have the solution?