lil php question about disabling postflood for some usergroups

Default postflood is:

PHP Code:

    if ($enablefloodcheck) {
      if ($bbuserinfo[userid]!=0 and time()-$bbuserinfo[lastpost]<=$floodchecktime and !ismoderator($foruminfo[forumid])) {
        eval("standarderror(\"".gettemplate("error_floodcheck")."\");");
        exit;
      }
    } 

But I want to disable it for usergroups 11 and 18 as well

I've tried

PHP Code:

if ($enablefloodcheck) {
      if ($bbuserinfo[userid]!=0 or $bbuserinfo[usergroupid]=!18 or $bbuserinfo[usergroupid]=!11 or !ismoderator($foruminfo[forumid]) and time()-$bbuserinfo[lastpost]<=$floodchecktime) {
        eval("standarderror(\"".gettemplate("error_floodcheck")."\");");
        exit;
      }
    } 

but this disables it for everyone. What am i doing wrong??

(this is in both newreply.php and newthread.php)

[DiscussAnything]

noone? please? It can't be all that complex, can it?