Swap Image doesn't work

[x3graphics]

Ok so I am having a little of a problem with DW Swap Image script. In Firefox it works just fine, but in IE when you click on the thumbnail that should swap the larger image it goes blank and then I have to right click on the larger image and click "Show Image". Here is the code I am using, I am not great at Javascript so I was hoping someone could help me out.
Function:
[quote]function MM_swapImage() { //v3.0
  var i,j=0,x,a=MM_swapImage.arguments; document.MM_sr=new Array; for(i=0;i<(a.length-2);i+=3)
  if ((x=MM_findObj(a[i]))!=null){document.MM_sr[j++]=x; if(!x.oSrc) x.oSrc=x.src; x.src=a[i+2];}
}[/quote]

Code on thumbnail:
[quote]<a href="javascript:void();"><img onclick="MM_swapImage('photo4','','http://www.woodz.com/2006/riders/fullimg/dylan_davis_1.jpg',1)" src="http://www.woodz.com/2006/riders/thumbs/dylan_davis_1.jpg" alt="" border="0"></a>[/quote]

If anyone can tell me whats going on that would be great.
Thank you