Could you confirm if you are recreating the RadTreeList on each Page_Init
(this must be so)? If you are already using Page_Init, does it not work if you set EnableViewState for the RadTreeList control itself?
the Telerik team
Registration for Q1 2011 What’s New Webinar Week is now open. Mark your calendar for the week starting March 21st and book your seat
for a walk through all the exciting stuff we ship with the new release!