Button Click event not firing

This is the second time im putting this question online. Sorry for that but I still cant get a way to fire a button event inside an update panel;

ID="UpdatePanel3" runat="server" UpdateMode="Always">
       <ContentTemplate>
           <asp:Panel ID="Panel3" runat="server" CssClass="HellowWorldPopup">
 
           <legend style="font-family: Tahoma; font-size: small; font-weight: bold; font-style: normal; font-variant: normal; text-transform: none; color: #000000; text-decoration: blink"> ICT UNAUTHORIZED USER
      </legend>
               <asp:Button ID="Button3" runat="server" Text="Button"  Style="display:none" />
               <asp:Button ID="Button4" runat="server" Text="OK" onclick="Button4_Click"
                   CausesValidation="true"/>
               <asp:Label ID="Label7" runat="server" Text="Label"></asp:Label>
               &nbsp;</asp:Panel>
           <asp:ModalPopupExtender ID="ModalPopupExtender12" runat="server" PopupControlID="Panel3" Enabled="true"
               TargetControlID="Button3">
           </asp:ModalPopupExtender>
 
       </ContentTemplate>
       <Triggers>
            <asp:AsyncPostBackTrigger ControlID="Button4" EventName="Click" />
 

          </Triggers>
   </asp:UpdatePanel>

I really dont know what the issue is and need some real help now please....
 
then in C# :

protected void Button4_Click(object sender, EventArgs e)
    {
        Response.Redirect("Login.aspx");
    }