I tried to reproduce this issue, I created a user control with a RadTabStrip, RadMultipage and RadGrid in one of the page views. However, everything is working fine in my case. I haven't set a dataSource for the grid and use the NeedDataSource event to populate the grid. The event is fired if I set AutoPostBack
to true for the tab strip.
Can you please be more specific about how exactly to reproduce this behavior (when the event is not fired).
the Telerik team