Way to force "I agree" checkbox before posting in specific forums?

[RedTurtle]

Hi Kh99,

So I am having an issue with the plugin.

I'm using the following code:

if ($GLOBALS['forumid'] != 99 AND is_member_of($bbuserinfo, 5,6,7))
{
   $vbulletin->input->clean_gpc('p', 'accept_rules', TYPE_BOOL);

   if (!$vbulletin->GPC['accept_rules'])
   {
       $errors[] = "<span style='color: #ba0000; background-color: #FDFD65;'>Please scroll down and accept the highlighted rules before submitting your post.</span>";
   }
}

Because I want it to show in all forums (put the 99 in there to make it work) and I want it to only apply to usergroups 5,6,7 (admin, mod, super mod).

Now if I use is_member_of($bbuserinfo, 5,6,7) it doesn't seem to work. If I put an exclamation in front of it then it works...but I'm not sure why...

EDIT: So here's the following things I've tried, as an admin:

if ($GLOBALS['forumid'] !=99 AND is_member_of($bbuserinfo, 5,6,7)) <== Doesn't work (lets me post)
if ($GLOBALS['forumid'] !=99 AND is_member_of($bbuserinfo, 2,3,4)) <== Works (lets me post)
if ($GLOBALS['forumid'] !=99 AND !is_member_of($bbuserinfo, 5,6,7)) <=== Doesn't let me as an admin post (so it works, but not sure why it needs an ! in front of is_member_of)