中央空调 几个外机:下面代码有问题吗,为什么不能实现图片不间断移动?

<tr>
<td width="232" height="21"><img src="tupian.files/zl.gif" width="232" height="84" /></td>
<td colspan="3" rowspan="2" bgcolor="#EEFFFF"><base href="http://localhost/home.asp">
<div id=demo style=overflow:hidden;height:33;width:200;background:#214984;color:#ffffff>
<table align=left cellpadding=0 cellspace=0 border=0>
<tr>
<td id=demo1 valign=top><img src="tupian.files/gd.jpg" width="150" height="108" /><img src="tupian.files/gd.jpg" width="150" height="108" /></td>
<td id=demo2 valign=top></td>
</tr>
</table>
</div>

<script>
var speed=30
demo2.innerHTML=demo1.innerHTML
demo.scrollLeft=demo.scrollWidth
function Marquee(){
if(demo.scrollLeft<=0)
demo.scrollLeft+=demo2.offsetWidth
else{
demo.scrollLeft--
}
}
var MyMar=setInterval(Marquee,speed)
demo.onmouseover=function() {clearInterval(MyMar)}
demo.onmouseout=function() {MyMar=setInterval(Marquee,speed)}
</script>
</td>
</tr>