- If you have more than 1 item in the RadComboBox, does the event fires? If not, have you check the AutoPostback property? it must be set to true (AutoPostback="true")
- If you have only 1 item in the RadComboBox, you should fill the RadGrid from code.
I'm not sure how you are filling the items for the RadComboBox, but other things you might want to consider are:
- Add a fixed item to the RadComboBox to always have one item. The item can have the text "Select an item" and a value of -1.
- Set the RadComboBox property AppendDataBoundItems="true" so when you bind your RadComboBox all items are added to the fixed one you have (even if there is only 1).
- With this you can always select the item in the combo thus firing the SelectedIndexChanged event.
Hope this helps.