I want change the color of the panel if i click checkbox using javascript

[itsenthil]

This is my userControl(ascx) file if run this one i got object required error........

What is wrong in that one plz help me....it is very urgent.....

<%@ Control Language="vb" AutoEventWireup="false" Codebehind="Usea.ascx.vb" Inherits="HIS.Usea" TargetSchema="http://schemas.microsoft.com/intellisense/ie5" %>
<script type="text/javascript" language="javascript">
        function output()
        {
         var xx = document.getElementById("cbtest").value;
        //var mainForm=document.mainForm.id("cbtest");
        if (xx.checked == true) 
        {
        document.getElementById("Panel1").style.backgroundColor= "#ffff00";
        return true;
        }
        if (xx.checked == false) 
        {
        document.getElementById("Panel1").style.backgroundColor= "#9acd32";
        return false;
        }
       }
</script>
<asp:panel id="Panel1" BackColor="YellowGreen" runat="server" Width="56px" Height="40px" BorderStyle="None"
    ToolTip="seat">
    <asp:Image id="Image1" Height="32px" Width="32px" runat="server" ImageUrl="file:///\\system107\HIS\Images\seat2.jpg"
        ImageAlign="Middle"></asp:Image>
    <INPUT id="cbtest" onclick="output()" type="checkbox" name="cbtest" runat="server">
    <asp:Label id="Label1" Width="32px" runat="server" Font-Names="Verdana" Font-Size="X-Small"></asp:Label>
</asp:panel>

[RedSon]

Moving to VB since its coded in VB. This might need to move around further but I'll let the helpful folks in VB take a shot at it first.

[itsenthil]

Moving to VB since its coded in VB. This might need to move around further but I'll let the helpful folks in VB take a shot at it first.

ok Thanks....