XF 1.5 Banner rotation not working

[Spartan]

I've successfully use the following to rotate ad banners. I recently created a new style, with no modifications - for some reason the banner rotation code doesn't work - both banners show up.

Any idea why this would work with one style, and not with another?

-------------


<xen:hook name="ad_above_top_breadcrumb" />

<br>
<br><center>
<table border="0" width="728" height="150">
<tr>
<td>

<script type="text/javascript">

this.randomad = function(){
var length = $("#adr li").length;
var ran = Math.floor(Math.random()*length) + 1;
$("#adr li:nth-child(" + ran + ")").show();
};

$(document).ready(function(){
randomad();
});

</script>

<ul id="adr">

<li><center>ad code here</center></li>
<li><center>ad code here</center></li>

</ul>
</td>
</tr>
</table>
</center>