Hi, I got information from here quite often.
I just want to share my experience this time and hope it might help someone someday.
I have a DropDownList in my GridView's PagerTemplate.
I used the example code from http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.gridview.pagertemplate(VS.80).aspx
I used it in many of my pages. All works fine except one.
The OnSelectedIndexChanged event just isn't fired in that one page.
Later I set the "EnableViewState" of that GridView to false, it works finally.
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