用JAVASCRIPT写一个幻灯代码，本人初学，查不出问题

<html>
<head>
<title>Image Slideshow Test</title>
<script language="javascript" type="text/javascript" src="slideshow.js">
</script>
</head>
<body>
<h1>Image Slideshow Test</h1>
<img class="slide" src="pic1.gif" width="1024" height="768">
<img class="slide" src="pic2.gif" width="1024" height="819">
<img class="slide" src="pic3.gif" width="555" height="417">
<img class="slide" src="pic4.gif" width="400" height="293">
<img class="slide" src="pic5.gif" width="1024" height="683">
<p>Click the image to view the next slide.</p>
</body>
</html>这是SLIDESHOW文件
var numslides=0,currentslide=0;
var slides=new Array();
function MakeSlideShow()
{
   imgs=document.getElementsByTagName("img");
   for(i=0;i<imgs.length;i++)
   {
      if(imgs[i].className!="slide") continue;
      slides[numslides]=imgs[i];
      if(numslides==0)
      {
         imgs[i].style.display="block";
      }
      else
      {
         imgs[i].style.display="none";
      }
      imgs[i].onclick=NextSlide;
      numslides++;
   }
}
function NextSlide()
{
   slides[currentslide].style.display="none";
   currentslide++;
   if(currentslide>=numslide) currentslide=0;
   slides[currentslide].style.display="block";
}
window.onload=MakeSlideShow;