ToolTip Image Button Does not Working?

[kallish]

Hi,

I have One ImageButton
<asp:HyperLink ID="ImgSearchUsr" runat="server" ImageUrl="~/Images/search_user.gif"></asp:HyperLink>
And I will TargetCOntrol Id For One ToolTip..

<telerik:RadToolTip runat="server" ID="RadTTSearch" Sticky="true" ShowEvent="OnMouseOver"
            Width="600px" ManualClose="true" TargetControlID="ImgSearchUsr" RelativeTo="Element"
            EnableViewState="true">
and In toolTip Control Its Contain One Search Button that is..

<asp:ImageButton ID="ImgSearch" runat="server" ImageUrl="~/Images/search.gif"  OnClick="ImgSearch1_Click" />             
                                 
</ToolTip>

My Problem Is this Within ToolTip Search Button(ImgSearch) OnClick Event Is not Working?

What is the Problem Plse Help Me..

Bye
kallish