In your AssemblyInfo.cs for the TimeLine you have the following definition:
[assembly:XmlnsDefintion("clr-namespace:Infragistics.Silverlight.Timeline;assembly=Infragistics.Silverlight.DataVisualization.Timeline.v9.2,"Infragistics.Silverlight.Timeline")]
wouldn't it make more sense if it was something like:
[assembly:XmlnsDefintion("http://infragistics.com/Datavisualization/Timeline;assembly=Infragistics.Silverlight.DataVisualization.Timeline.v9.2)]
?
Your suggestion makes sense, but this naming doesn't work in SL.