Hi,
I have been struggeling a few hours with a MapTips-problem now, so I might as well share what I found out.
I have a GraphicsLayer where I add some polygon features from a query. And the GraphicsLayer has its MapTips set to show some attributes. On the GraphicsLayer I have a UniqueValueRenderer set, with FillSymbol and a Path in the ControlTemplate of the symbol. Everything draws nicely, but the MapTips weren't showing at all. It turns out that when I changed the symbol to a SimpleFillSymbol, the MapTips shows as expected.
This might be "by design", or a "feature" of Silverlight, but it took me some time to figure it out...
