Can't check more than one RadioButton across multiple items in a Treeview

I’m using a TreeView control to present a list of Questions. Using the Prism.DataTemplateSelector, I'm loading a View (.xaml file) that represents a single Question into each node in the TreeView. In the View for that question is a ListBox containing RadioButtons (one for each item in a Picklist object that the ListBox is bound to).

The radio b开发者_如何学编程uttons work as expected for the question, but when I check a RadioButton on another node/question in the TreeView, the check for the button in the Question I was editing before disappears. In other words, I'm only able to check one RadioButton in the whole list of Questions/Items bound to the containing TreeView. How do I group the RadioButtons in the ListBox to the scope of the single question instead of all the questions in the TreeView.

RadioButton.GroupName is the property you are looking for