private async void Delete_Click(object sender, RoutedEventArgs e)
        {
            //delete the current detail
            try
            {
                int id = int.Parse(EventId.Text);
                viewModelMain.DeleteContact(id);
            }
            catch
            {
                MessageDialog md = new MessageDialog("There is no data", "No data");
                await md.ShowAsync();

                EventId.Focus(FocusState.Programmatic);
                EventId.SelectAll();
                return;
            }
            Frame.Navigate(typeof(AppointmentPage));
        }