Hello,
if your code is not worked than also try with the below code snippet.
GridEditableItem editedItem = e.Item
as
GridEditableItem;
UserControl userControl = (UserControl)e.Item.FindControl(GridEditFormItem.EditFormUserControlID);
Also try to access same control into ItemDataBound event.
Let me know if any concern.
Thanks,
Jayesh Goyani