UnauthorizedAccessException while initializing ProximityDevice (Windows Phone)

Question

I want to use ProximityDevice in my application. If I declare it as field or in the constructor, like this:

public partial class MainPage : PhoneApplicationPage {
    // Constructor
    public ProximityDevice device;
    public MainPage() {
        InitializeComponent();
        device = ProximityDevice.GetDefault(); 
    }
}

or this:

public partial class MainPage : PhoneApplicationPage {
    // Constructor

    public MainPage() {
        InitializeComponent();
       public ProximityDevice device = ProximityDevice.GetDefault(); 
    }
}

I get

A first chance exception of type 'System.UnauthorizedAccessException' occurred in SecurityClient.DLL
A first chance exception of type 'System.Reflection.TargetInvocationException' occurred in mscorlib.ni.dll
A first chance exception of type 'System.Reflection.TargetInvocationException' occurred in Microsoft.Phone.ni.dll

If I declare it as static code causes no problems:

 public partial class MainPage : PhoneApplicationPage {
        // Constructor
        public static  ProximityDevice device = ProximityDevice.GetDefault();
        public MainPage() {
            InitializeComponent();       
        }
    }

How to fix that problem?

Answer 1

Make sure you added the ID_CAP_PROXIMITY capability to your application manifest.