in_array(): Wrong datatype for second argument

[sabret00the]

PHP Code:

     $grps_ids = explode(' ', trim($bbuserinfo['grps']));
     if (!$do)
     {
         //gonna use this to direct em to the right form
         if (in_array($grps_ids, $grps_showgroup['groupid']))
 //        if (in_array($bbuserinfo[grps], $grps_showgroup['groupid']))
         {
             // send to leave
             $url = "membership.php?$session[sessionurl]do=leavegroup&g=$groupid";
             eval(print_standard_redirect('redirect_rightform'));
         }
         else
         {
                 echo "<!-- ".$grps_showgroup[groupid]." -->"; 
                 echo "<!-- ".print_r($grps_showgroup, TRUE)." -->"; 
 
             // send to join
             //$url = "membership.php?$session[sessionurl]do=joingroup&g=$groupid";
             //eval(print_standard_redirect('redirect_rightform'));
         }
     
     } 


i don't quite get what i'm doing wrong here, i'm giving it an array then i'm asking it if a number is in there?