Map control cannot display its content?
There are some articles available in the Internet where You can read about the issue. I found that the reason can be related to third party additional elements like animated controls, which consumes lots of resources especially when You work with WP7 Emulator and 256 MB of RAM ( - recommended by Nokia btw ;) ).
I decided to check each element - one by one - by removing it from the code. Then I launched the app using the Emulator. I noticed that the problem was: ATTENTION - ANIMATED ELEMENT FROM TELERIK UI LIB - RadBusyIndicator
I put even two RadBusyIndicator controls in the same page's code where Map control was crucial and the primary element. After removing them both I got:
So the reason can be one or more of such elements existing in Your code - consider this and test the solution if You have similar problem with displaying Map's content.