Events not being called from within UpdatePanel

I have a gridview in an updatepanel which works fine. I put a asp:button with an onclick (or an input type=submit runat=server onserverclick=) *outside* the update panel and the function it calls gets hit but with a full postback. If I move the button *inside* the update panel the event does not get hit. Any ideas why? I was able to get it to work by manually getting the Request.Form value in the page_load instead of relying on the event but would like to know why the event wouldn't fire.

put the script here plz .