js无缝水平左滚动图片，只滚动一次就不滚动了，请问下是为什么？

[ruiandli]

<div id=demo style="background: #ffffff; overflow: hidden; width: 1002px; height: 130px">
<table cellPadding=0 align=center border=0 cellspace="0" width="1002">
<tr>
<td id=demo1 vAlign=top>
<% call ShowPicArticle(18,10,20,1,10,130,90,200,false,false) %>
</td>
<td id=demo2 vAlign=top>xxb</td>
</tr>
</table>
</div>
<script>
(function(){
var speed=30;
demo2.innerHTML=demo1.innerHTML;
function Marquee(){
if(demo2.offsetWidth-demo.scrollLeft<=0)
demo.scrollLeft-=demo1.offsetWidth;
else
demo.scrollLeft++;
}
var MyMar=setInterval(Marquee,speed);
demo.onmouseover=function(){
clearInterval(MyMar);
}
demo.onmouseout=function(){
MyMar=setInterval(Marquee,speed);
}
})();
</script>
通过调用 <% call ShowPicArticle(18,10,20,1,10,130,90,200,false,false) %>显示图片。显示的是10张图片。