四尺中堂书法:麻烦帮忙一下

==在网页上,图像只从右滚动到左一圈便不动了,我想让它不停的滚动,怎么办啊,是不是代码有错误啊,哪里错了呢!
<tr>
<td height="150" bgcolor="#FFFFF4" width="540">
<table border="0" width="536" id="table19" height="151" cellspacing="0" cellpadding="0">
<tr>
<td>
<style type="text/css">
<!--
body {
background-color: #FCF5EB;
topmargin:0;
leftmargin:0;
}
-->
</style>
<DIV id=demo style="OVERFLOW: hidden; WIDTH: 539px; height:153px">

<TABLE border=0 align=center cellPadding=0 cellspacing="0" cellspace="0" width="524" height="150">
<TBODY>
<TR>
<TD id=demo1 width="515">
<table width="469" border="0" cellpadding="0" cellspacing="0" bgcolor="#FCF5EB" height="144">
<tr align="center">

<td width="150">
<img src="image/cwbx.jpg" width="150" height="150" border="0" class=box></td>

<td width="160">
<img src="image/qcxl.jpg" width="150" height="150" border="0" class=box></td>

<td width="159">
<img src="image/tot.jpg" width="150" height="150" border="0" class=box align="left"></td>

</tr>
</table>
</TD>
<TD vAlign=bottom bgcolor="#FCF5EB" id=demo2 width="0"></TD>
</TR>
</TBODY>
</TABLE>
</DIV>
<SCRIPT>
var Picspeed=15
demo2.innerHTML=demo1.innerHTML
function Marquee1(){
if(demo2.offsetWidth-demo.scrollLeft<=0)
demo.scrollLeft-=demo1.offsetWidth
else{
demo.scrollLeft++
}
}
var MyMar1=setInterval(Marquee1,Picspeed)
demo.onmouseover=function() {clearInterval(MyMar1)}
demo.onmouseout=function() {MyMar1=setInterval(Marquee1,Picspeed)}
</SCRIPT></td>
</tr>
</table>

</td>
</tr>