Hey.

Well It was working for the secondary user-group. Although I found out that I needed one for the primary group. So Amykhar helped me out with this slight modification of the script... Works on my board (3.5.4).
PHP Code:
switch($userinfo['field5'])
{
case "A":
$userdata->set('usergroupid', 12);
break;
case "B":
$userdata->set('usergroupid', 13);
break;
case "C":
$userdata->set('usergroupid', 18);
break;
}
Talk to you later,
Paul F