Ajax Toolkit ModalPopup Postback to run server side code behind

Issue:
You use Ajax Toolkit to display a modal poup up. But you would like to run some code behind function (C#/Vb.net) when OK button is clicked. But the event never fires!

Solution:
Make sure you don't specify the OkCOntrolID and OnclientScript properties in the POPUP Extender. See below.