void INotificareCallback.OnError(NotificareError error)
 {
     Console.WriteLine ("error adding device tags: " + error.Message);
 }
 void INotificareCallback.OnError(NotificareError error)
 {
     Console.WriteLine ("error registering device: " + error.Message);
 }
 void BillingManager.IOnRefreshFinishedListener.OnRefreshFailed(NotificareError error)
 {
     Console.WriteLine ("billing refresh failed: " + error.Message);
 }