I've checked the image attached to the previous post once again. Looking at the errors you are getting I suppose that something went wrong with the assemblies. The mark-up looks correctly defined.
Some customers experience problems similar to the yours and this option helped to resolve this problem.
You could check the following forum thread
for further reference. The same is applicable to WPF, as well.
In order to avoid additional round trips, I believe that the best option would be to try to isolate the problem in a runnable project. It could be attached in a separate support thread and would help us a lot.