when mouse over the hotspot, IE status bar displayed "Error on Page".

my code as below:

<%@ Page Language="C#" MasterPageFile="~/MasterPage.master" Title="?????????" %>
<asp:Content ID="Content1" runat="server" ContentPlaceHolderID="ContentPlaceHolder1">
<form id="Display_Sample" action="~/products.aspx" method="POST">
<table style="width:450px;height:550px">
    <tr style="width:100%; height:450px">
    <td>
   <asp:image id="DisplayProduct" runat="server" ImageUrl="~/Images/Sample_CanadianWinter.gif" AlternateText="???"/>
    </td>
    </tr>
    <tr style="width:100%; height:100px"><td>
    <img style="border:0" id="Product_Grid" runat="server" src="~/Images/Sample_Grid10Ft.gif" mce_src="~/Images/Sample_Grid10Ft.gif" usemap="#DisplayProductPallet" alt=""/>
    </td>
    </tr>
</table>
    <map id="DisplayProductPallet">
    <area shape="rect" coords="5,5,100,105" href="http://forums.asp.net/AddPost.aspx?ForumID=15#" mce_href="http://forums.asp.net/AddPost.aspx?ForumID=15#" alt="Canadian Winter"
    onmouseover="window.document.Content1.ContentPlace Holder1.Display_Sample.DisplayProduct.ImageUrl='~/Images/Sample_CanadianPaint.gif'"/>
    </map>
</form>

</asp:Content>

is it correct I am using window.document...?

The problem here is that the client knows nothing about .NET. Therefore, using an object oriented naming pattern has no meaning. Look are the emitted HTML for this page and you are going to see something much different in the image control's name and ID attribute. However, don't just use what you see there as it might change depending on the behavior of the page (those are names generated by the ASP.NET runtime). Ideally, you should write some codebehind to emit the javascript with the unique client ID of the image control. You might be able to get away with something like this:

<area shape="rect" coords="5,5,100,105" href="http://forums.asp.net/AddPost.aspx?ForumID=15#" mce_href="http://forums.asp.net/AddPost.aspx?ForumID=15#" alt="Canadian Winter" onmouseover="<%=DisplayProduct.ClientID%>.url='~/Images/Sample_CanadianPaint.gif'"/>

This should emit the DisplayProduct image control unique clientID to the area tag.

-Peter
peterlanoie.blog

Oh, and I had something wrong... it should be ".src" not ".url" for the client side image url attribute of the image. Also, using the ~ syntax in the client side doesn't work either. You need to fully qualify the image URL.

Try this:

<area shape="rect" coords="5,5,100,105" href="http://forums.asp.net/AddPost.aspx?ForumID=15#" mce_href="http://forums.asp.net/AddPost.aspx?ForumID=15#" alt="Canadian Winter" onmouseover="<%=DisplayProduct.ClientID%>.src='<%= ResolveUrl("~/Images/Sample_CanadianPaint.gif")%>'"/>

-Peter
peterlanoie.blog