我想实现 巧学巧用 文字滚动 js哪里出错了？

<%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" %><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>无标题页</title>
</head>
<body  background="aa.jpg">    <form id="form1" runat="server">
    
     <table width="543" border="0" cellpadding="0" cellspacing="0"  >
     <tr>
     <td valign="bottom">
     <div style="width:543px; height:21; overflow:hidden"  onMouseOver="stop()" onMouseOut="start()">
    </div>
    
     </td>
     </tr>
     </table>
    
    
    <table width="543" border="0" cellpadding="0" cellspacing="0" id="scrollimg" >
    <tr>
    <td id="simg">
    <table width="543" border="0" cellpadding="0" cellspacing="0" >
    <tr>
    <td nowrap="nowrap">
    
    
    <font color="#FF6C02">*</font><a href="#">1.巧学巧用dfsdgdsgdfgfgdfdsfgdsgdf</a>
     <font color="#FF6C02">*</font><a href="#">2.巧学巧用dfgfdsgsdfgdsfgdsfgdsf</a>
      <font color="#FF6C02">*</font><a href="#">3.巧学巧用dfgdsdsfgdsgd</a>
    </td>
    </tr>
    </table>
    
    </td>
    <td id="simg1"></td>
    </tr>
    </table>
     <script language="javascript" type="text/javascript">
     function newsScroll()
     {
     if(scrollimg.parentNode.scrollLeft!=(scrollimg.clientWidth/2))
     scrollimg.parentNode.scrollLeft++;
     
     else
     scrollimg.parentNode.scrollLeft=0;     
     }    var tm=null
    function window.onload(){
    simg1.innerHTML=simg.innerHTML    tm=setInterval('newScroll()',20)    }    function stop(){
    clearInterval(tm)
    }     
    function start()
    {
    tm=setInterval('newScroll()',20)
    
    }
     </script>
    
    </form>
    
</body>
</html>