hello guys, i ve got a problem with my programm. here is the link: http://dl.dropbox.com/u/2734432/TabbedInterface.7z once u have opened both tabs, u ll start loosing the references to other collections of the current item in the view. that is because these ids are nullable and once you switch over to the other tab they ll become null. my question is why and how can i corrent that behavoir? if you change the int? to int there are no more problem, but i need them to be nullable!