Adding Map Graphics Layer at 3.1

[JosephCox]

I am trying to add a Map Graphics layer to my map and I am using this sample as a guide:
http://resources.arcgis.com/en/help/windows-mobile-sdk/concepts/index.html#/Custom_Layer_Extension/0...

The sample uses:

MobileApplication.Current.Project.SharedMap.MapGraphicsLayers.Add(myGraphicsLayer);

to add a graphics layer but at it seems like shared map is not available at 3.1

I have tried to create a Graphic Layer and add it to the map like this:

MapGraphicLayer mapGraphicLayer = new MapGraphicLayer("Offset");
MobileApplication.Current.Project.Map.MapLayers.Add(mapGraphicLayer);

but that doesn't work. Any suggestions?