datalist 文字不间断滚动

<%@ Control Language="C#" AutoEventWireup="true" CodeFile="List_Left.ascx.cs" Inherits="Web_Control_List_Left" %>
<div id="demo" style="border: 0px; overflow: hidden; height: 204px; width: 186px;
    float: left; margin-left: -5px;">
    <table id="demo" style="margin-left: -7px; border: 0px; width: 188px;">
        <tr>
            <td id="demo1">
                <asp:DataList ID="dtZS" runat="server" Width="188px">
                    <ItemTemplate>
                        <table width="100%" cellpadding="2" cellspacing="1">
                            <tr>
                                <td style="width: 8px;">
                                    <img src="../Content/images/Arrow_triangle.gif" alt="" style="width: 4px; height: 8px;" />
                                </td>
                                <td width="178px" align="left" valign="top">
                                    <a href="Show_news.aspx?id=<%# Eval("id")%>" title="<%# Eval("T_NewsTitle") %>">
                                        <%# Eval("T_NewsTitle").ToString().Length > 12 ? Eval("T_NewsTitle").ToString().Substring(0, 12) + "..." : Eval("T_NewsTitle")%></a>
                                </td>
                            </tr>
                        </table>
                    </ItemTemplate>
                </asp:DataList>
            </td>
        </tr>
        <tr>
            <td id="demo2">
            </td>
        </tr>
    </table>
</div><script type="text/javascript">//向上滚动  
var speed=30
demo2.innerHTML=demo1.innerHTML//克隆demo1为demo2
function Marquee(){
if(demo2.offsetHeight-demo.scrollTop<=0)//当滚动至demo1与demo2交界时
demo.scrollTop-=demo1.offsetHeight//demo跳到最顶端
else{
demo.scrollTop++
}
}
var MyMar=setInterval(Marquee,speed)//设置定时器
demo.onmouseover=function() {clearInterval(MyMar)}//鼠标移上时清除定时器达到滚动停止的目的
demo.onmouseout=function() {MyMar=setInterval(Marquee,speed)}//鼠标移开时重设定时器                 
</script>//这个是我的代码  但是不起作用 纠结了半天了 不知道哪里出现错误 请大侠们指点一下 帮我解决这个问题   或者有单个的例子可以给我一份学习 先谢谢  [email protected]