"CMN-102" "message" : "Resource for parameter [deviceId] is not found"

Have been successfully issuing CallOut's from C# SDK using deviceId. Now, all of a sudden I'm getting this "resource for parameter is not found". I'm using the same deviceId as I have been. I then went out and checked for all my device id's using

rc.Restapi().Account().Extension().Device().Get();

and it's returning the same deviceId. What's wrong now?

Thanks