logging out form external page error, help please

[zecryan]

I am trying to create a logout button on my main site like

localhost/kaizendigital/forums/login.php?do=logout&logouthash="whatever"

but the hash i am getting is not the same that the forums logouthash is. I am getting it by this sql statement:

SELECT sessionhash FROM session WHERE userid = '{$vbulletin->userinfo['userid']}'

is that the wrong one? is the any encode like MD5 i need to do to it? I could not find a tutorail on this and would like a little help. Thanks.