Getting banners to display in wordpress loop

[craven2]

Here's my PHP code here.

<?php

function my_ads(){
  global $wp_query;

  $adCount = count($bannerAd);
  $randomAdNumber = mt_rand(1, $adCount);
  if (is_home() && $wp_query->current_post == 0) {
    echo <<<END
      <center><script type="text/javascript">
      show_banners('top1');
      </script></center>
END;
  }

  if (is_home() && $wp_query->current_post == 2) {
    echo <<<END
      <center><script type="text/javascript">
      show_banners('topb');
      </script></center>
END;
  }

  if (is_home() && $wp_query->current_post == 4) {
    $t = time();

echo <<<END
  <IFRAME SRC="http://ad.doubleclick.net/adi/N5648.289555.ABLEMAGAZINE.CO.UK/B5106955.4;sz=600x120;ord=$t?" WIDTH=600 HEIGHT=120 MARGINWIDTH=0 MARGINHEIGHT=0 HSPACE=0 VSPACE=0 FRAMEBORDER=0 SCROLLING=no BORDERCOLOR='#000000'>
  <SCRIPT language='JavaScript1.1' SRC="http://ad.doubleclick.net/adj/N5648.289555.ABLEMAGAZINE.CO.UK/B5106955.4;abr=!ie;sz=600x120;ord=$t">
  </SCRIPT>
  <NOSCRIPT>
  <A HREF="http://ad.doubleclick.net/jump/N5648.289555.ABLEMAGAZINE.CO.UK/B5106955.4;abr=!ie4;abr=!ie5;sz=600x120;ord=$t">
  <IMG SRC="http://ad.doubleclick.net/ad/N5648.289555.ABLEMAGAZINE.CO.UK/B5106955.4;abr=!ie4;abr=!ie5;sz=600x120;ord=$t?" BORDER=0 WIDTH=600 HEIGHT=120 ALT="Advertisement"></A>
  </NOSCRIPT>
  </IFRAME></center>
END;
  }
}
?>

It parses with no errors, but when I insert it into my website, the ads appear in the source code; but I can't visually see them on the page.