How to redirect usergroups during login?

[org]

I wish to redirect certain usergroups to specified areas of the forum, using login.asp. Im using the code below:

if ($bbuserinfo['usergroupid'] == 9)
{
header("Location: http://www.mysite.com/customers/forumdisplay.php?f=5");
}

In my world, this checks to see if the user logging in belongs to usergroup 9, and then redirects them to forum 5. Problem is that when I try to insert this into login.asp it doesnt have any effect. I just end up at the same page, but being logged in.

Is the syntax correct and/or where should I insert it?