it requires mapping to "clr-namespace:System.ComponentModel;assembly=WindowsBase" and "clr-namespace:System.Windows.Data;assembly=PresentationFramework". I can find both WindowsBase.dll and PresentationFramework.dll but these are the ones build against .NET and so won�??t work with Silverlight. I don't appear to have a Siliverlight one in my reference assemblies. Anyone got any bright ideas?