Link to topic in profile/postbit?

[ray-]

I got this working:

<if condition="$post[field5]"><a href="showthread.php?t=$post[field5]"><img class="inlineimg" src="images/xtreme/statusicon/diary.gif" alt="Diary of $post[username]" border="0" /></a></if>

But now I want to show this icon only if that user is in a specific usergroup.
I tried this:

 <if condition="is_member_of($bbuserinfo, 1)">
              <div>
<if condition="$post[field5]"><a href="showthread.php?t=$post[field5]"><img class="inlineimg" src="images/xtreme/statusicon/diary.gif" alt="Diary of $post[username]" border="0" /></a></if>
              </div>
</if>

But that doesn't work.
I've searched the forums, but it looks like using ' <if condition="is_member_of($bbuserinfo, 1)">' is the only way to do this. What am I doing wrong here?