If you call Page.DataBind() in the Page_Load event handler of a page that has a RadPivotGrid on it that has an event handler for OnNeedDataSource, the OnNeedDataSource event isn't raised when the page is loaded. This behavior is different than that of other controls such as RadGrid. In my opinion it is confusing and the behavior should be the same. You may have other controls on the page that you want to data bind. So, I think it is reasonable that you should be able to call DataBind() and use advanced binding with RadPivotGrid at the same time. Also, I noticed that if you don't call DataBind(), the OnNeedDataSource event is raised twice.

Please see the Visual Studio 2012 project that I attached to this bug report for example code. Set break points in the NeedDataSource event handlers for the RadPivotGrid and RadGrid controls and run the application in debug mode to see the behavior. Comment and uncomment the call to DataBind() in Page_Load().