Session_register problem

[kid A]

For some reason this code does not work as intended:

$kundetype = htmlspecialchars( stripslashes($row['btype']));
        $b_id = htmlspecialchars( stripslashes($row['brukerid']));        
        if ($num_results > 0) {            
            session_register("innlogget", "tilgang", "sessbrukerid");
            $innlogget = $navn;
            $tilgang = $kundetype;
            $sessbrukerid = $b_id;                        
        } 

The $innlogget and $tilgang variables are set with the right value, but somehow $sessbrukerid is set the same value as $tilgang ($kundetype).

Why does this happen? I've made sure to deregister all session variables one by one and destroy the session upon logout, but it still happens the next time I log in.