如何使用RenderControl注册回发事件？

I am using RenderControl in a string builder to add a dropdownlist in a asp:TreeView. My dropdownlist is set to autopostback and I have an event on the SelectedIndexChanged attached. Unfortunaltly, I see my dropdownlist correctly populated inside my treeview, but changing the selection ain't raising events.I am using RenderControl in a string builder to