<script type=”text/javascript”>
 var random_number = Math.random();
 if (random_number < .5){
  //your first ad unit code goes here
 } else {
  //your second ad unit code goes here
 }
</script>
<script type="text/javascript"  src="http://pagead2.googlesyndication.com/pagead/show_ads.js"></script>

<script type=”text/javascript”>
 var random_number = Math.random();
 if (random_number < .5){
<script type="text/javascript"><!--
google_ad_client = "#*$!";
google_ad_width = 728;
google_ad_height = 90;
google_ad_format = "728x90_as";
google_color_border = "FFFFFF";
google_color_bg = "FFFFFF";
google_color_link = "000000";
google_color_url = "999999";
google_color_text = "666666";
//--></script>
 } else {
<script type="text/javascript"><!--
google_ad_client = "#*$!";
google_ad_width = 468;
google_ad_height = 60;
google_ad_format = "468x60_as";
google_color_border = "FFFFFF";
google_color_bg = "FFFFFF";
google_color_link = "000000";
google_color_url = "999999";
google_color_text = "666666";
//--></script>
 }
</script>
<script type="text/javascript"  src="http://pagead2.googlesyndication.com/pagead/show_ads.js"></script>

and not only does it not rotate but I also get an attractive "} else { }" under all my 468 banners. I am a JS fool, can someone shove me in the right direction. :-)

I first tried without the <script type="text/javascript"><!-- part, that is: only including the lines beginning "google", but then the ad never even displayed! I'm surprised AS blog didn't post a fuller example.