After First Post Condition

[ntock]

For some reason I can't get this bad boy to work, i.e. I'd like to be able to show this adsense after every first post on a page of forum 24:

<if condition="!$GLOBALS['FIRSTPOSTID']">
<if condition="in_array($forumid, array('24'))">
$spacer_open
<div style="padding:0px 0px $stylevar[cellpadding]px 0px">

<table class="tborder" cellpadding="$stylevar[cellpadding]" cellspacing="$stylevar[cellspacing]" border="0" width="100%" align="center">
<tr>
    <td class="thead" align="left">Sponsored Links</td>
</tr>
<tr>
    <td class="alt1" align="center">
<script type="text/javascript"><!--
google_ad_client = "xxxxxxxxxxxxxxxxxx";
google_ad_width = 728;
google_ad_height = 90;
google_ad_format = "728x90_as";
google_ad_type = "text_image";
//2007-01-07: xxxxxxxxxxxxxxxxxxxxx
google_ad_channel = "xxxxxxxxxxxxxxxxxx";
google_color_border = "FFFFFF";
google_color_bg = "FFFFFF";
google_color_link = "0066CC";
google_color_text = "000000";
google_color_url = "3D81EE";
//--></script>
<script type="text/javascript"
  src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
</script>
</if>
    </td>
</tr>
</table>

</div>
$spacer_close
</if>  
</if>

Anybody know what I'm doing wrong (I have this at the bottom of my postbit_legacy). Many thanks in advance!