private void OnCreateDoc(object sender, RoutedEventArgs e) { if (_menus.Count == 0) { MessageBox.Show("Select a date first", "Menu Planner", MessageBoxButton.OK); return; } var page2 = new MenuDocumentPage(); NavigationService.LoadCompleted += page2.NavigationService_LoadCompleted; NavigationService.Navigate(page2, _menus); // NavigationService.Navigate(new Uri("pack://application:,,,/DocumentPage.xaml"), menus); }