AJAX :: Getting A Function To Run On OK When ModalPopupExtender Is Called?

I'm having some trouble getting this to work. basically I got the modalpopup to show, and when it's shown i have 2 buttons (Yes and Cancel). When yes is clicked i want a function to be called. Here is my asp.net code:

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<asp:Button ID="btnMpeDummy" runat="server" Text="Test" style="display:none" />
<ajaxtk:ConfirmButtonExtender ID="cbeDelScn" runat="server" TargetControlID="btnMpeDummy" DisplayModalPopupID="mpeDelScn" />
<ajaxtk:ModalPopupExtender ID="mpeDelScn" runat="server" TargetControlID="btnMpeDummy" PopupControlID="pnlDelScn" OkControlID="btnDelScnYes" CancelControlID="btnDelScnCancel" BackgroundCssClass="modalBackground" />
<asp:Panel ID="pnlDelScn" runat="server" CssClass="modalDialog" style="display:none; width:300px;">
<asp:UpdatePanel ID="upnl3" runat="server" ><ContentTemplate >
<asp:Label ID="lblDelScn" runat="server" Text="Delete Iteration" />
</ContentTemplate></asp:UpdatePanel><br /><br />
<asp:Button ID="btnDelScnYes" runat="server"
Text="Yes"
ToolTip="Yes"/>
<asp:Button ID="btnDelScnCancel" runat="server"
Text="No"
ToolTip="No" />
</asp:Panel>

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And here is my VB code:

Protected Sub btnDelScnYes_Click(ByVal sender As Object, ByVal e As UI.UIIterationList.IterationListEventArgs) Handles btnDelScnYes.Click
Dim scn As dat.Iteration = New dat.Iteration(e.iterationID, SessUserID)
scn.DeleteIteration()
Response.Redirect("Calibration.aspx")
End Sub

Not sure if this is useful, but just some info: My page have a list of iterations. there are several columns to this table. when the last column is clicked, the modal popup shows and asks the user if to confirm if he/she wants to delete this iteration which is this code:

Dim scn As dat.Iteration = New dat.Iteration(e.iterationID, SessUserID)
scn.DeleteIteration()

so i'm trying to get the funtion to be called, but it's not working. when you click "OK" nothing happens. when i debug it and trace the logic it doesn't even go into the above VB subroutine.