Can You See Why This Still Does Not Work?

This script is supposed to be a banner rotator script.
I still can't find where the error is that keeps it from working.
Would any of you be able to correct it?
Thanks!

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<script type="text/javascript">
<!-- Begin
rnd.today=new Date();
rnd.seed=rnd.today.getTime();

function rnd() {
rnd.seed = (rnd.seed*9301+49297) % 233280;
return rnd.seed/(233280.0);
};

function rand(number) {
var result = Math.ceil(rnd()*number);
if (!result)result++;
return result
};
var ad_cnt4 = 4;
var ad4 = rand(ad_cnt4);
var link4;
var adBanner4;
var width4
var height4
if (ad4==1) {
link4="http://clickserve.cc-dt.com/link/click?lid=##########";
adBanner4="http://www.bellbookandcandlepublications.com/greenwoodsvillage/images/adbanners/new%20rules%20marketing.jpg";
width4="130";
height4="";
alt4="New Rules of Marketing";
}
if (ad4==2) {
link4="http://clickserve.cc-dt.com/link/click?lid=#########";
adBanner4="http://www.bellbookandcandlepublications.com/greenwoodsvillage/images/adbanners/facebook%20marketing.jpg";
width4="130";
height4="";
alt4="Facebook Marketing";
}
if (ad4==3) {
link4="http://clickserve.cc-dt.com/link/click?lid=###########";
adBanner4="http://www.bellbookandcandlepublications.com/greenwoodsvillage/images/adbanners/internet%20riches.jpg";
width4="130";
height4="";
alt4="Internet Riches";
}
if (ad4==4) {
link4="http://clickserve.cc-dt.com/link/click?lid=##########";
adBanner4="http://www.bellbookandcandlepublications.com/greenwoodsvillage/images/adbanners/aff%20market%20on%20web.jpg";
width4="130";
height4="";
alt4="Affiliate Marketing on the Web";
}
document.write('<center><a href="' + link4 + '" target="_blank">');
document.write('<img src="' + adBanner4 + '" width=' + width4 + ' height=' + height4 + ' border=0 alt="' + alt4 + '"></a>');
document.write('</center>');
// End -->
</SCRIPT>

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