关于跑马灯无法运行的问题

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>无标题文档</title>
</head><body>  <DIV   id=demo   style="OVERFLOW:   hidden;   WIDTH:   292px;   HEIGHT:   90px">   
                              <TABLE   cellSpacing=0   cellPadding=0   width="100%"   border=0>   
                                      <TR>   
                                          <TD   id=demo1><img src="../gameMan/fishbone_gumball.jpg" width="140" height="80"><img src="../gameMan/fishbone_gumball.jpg" width="140" height="80"><img src="../gameMan/fishbone_gumball.jpg" width="140" height="80"><img src="../gameMan/fishbone_gumball.jpg" width="140" height="80"><img src="../gameMan/fishbone_gumball.jpg" width="140" height="80"><img src="../gameMan/fishbone_gumball.jpg" width="140" height="80"></TD>   
                                          <TD   id=demo2></TD>   
                                      </TR>   
                              </TABLE>   
                          </DIV>   
    
                              <SCRIPT>   
      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></body>
</html>
这段代码是可以在单个纯html文件中运行的可是我需要在我自己的网页中运行这个代码，却死活不动，我用的div+css，而且我在这个文件中还有其他的js脚本是不是有冲突，主要是与哪些代码会发生冲突，谢谢啦……