i have a problem with a special counter

[dom' puiu]

I have the following problem:
in my forum i have a special counter. i want this counter to apper in the showthread section of the forum. but only at the users from some usergroups i set.
i modified the postbit template:
<if condition="in_array('$bbuserinfo[usergroupid]', $groupidul)">
$vboptions[spc_name]: $post[spc_posts]<br>
</if>

and in the phpinclude_start i have put this:

$groupidul=explode(", ",$vboptions['spc_forumid']);

but i get the following error:
Warning: in_array(): Wrong datatype for second argument in /home/virtual/site13/fst/var/www/html/forum/includes/functions_showthread.php(640) : eval()'d code on line 67

i know that it sais the $groupidul is not an array but i dont know why