New Post: Why MainPage.xaml can't be in the Views Namespace in WP7 Project?

Excuse me, As the title Asked, if I put the MainPage.xaml Into the Views Namespace, When I Call the PreRequest<MainPageViewModel>() And After Initialized, it will throw a Exception.

If I put the MainPage.xaml Into the Top Namespace instead of Views.MainPage, it will be work.

The other page or views which put into the Views NameSpace will no occur this problem?