[Jase2]

He is correct. You are not allowed to use Iframes -- but the ad can go there.

Here is the correct way:

FIND:

<!-- message -->
  <div id="post_message_$post[postid]">$post[message]</div>
   <!-- / message -->

Replace with:

<!-- message -->
        <div id="post_message_$post[postid]">
<if condition="($post[postcount]==1) and ($show['guest'])">
<div style="float: right; margin: 0 0 5px 5px;">
        <script type="text/javascript"><!--
google_ad_client = "pub-0574157151562455";
/* 250x250, created 28/03/08 */
google_ad_slot = "5276949639";
google_ad_width = 250;
google_ad_height = 250;
//-->
</script>
<script type="text/javascript"
src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
</script>
<br />
</div>
</if>
$post[message]
</div>
        <!-- / message -->

Change to match your set-up!

Anyway, where would I edit to get my ads to down the right hand side of a thread? Am I right in thinking somewhere in the 'showthread' template?

Regards Jason