problem in program

Nov 29, 2011 at 8:14 AM

there are many problem,I can't debug this problem.

such as:

Error 3 The type or namespace name 'Shell' does not exist in the namespace 'Microsoft.Phone' (are you missing an assembly reference?) 

Error 37 The type or namespace name 'PhoneNavigationEventArgs' could not be found (are you missing a using directive or an assembly reference?)

Error 10 The type or namespace name 'Navigation' does not exist in the namespace 'Microsoft.Phone' (are you missing an assembly reference?) 

Error 40 'object' does not contain a definition for 'OnNavigatedTo' 

I use sdk7.1.what I can do to debug this program well?