Notification Android does not work

Question

I followed the example given here of stackoverflow,

Notifications in a given time and on mobile phone

but only the service is started, the notification is not launched. Follow my code here, how I resolve this situation?

public class StartUpBootReceiver extends BroadcastReceiver {

     @Override
     public void onReceive(Context context, Intent intent) {

            if (Intent.ACTION_BOOT_COMPLETED.equals(intent.getAction())) {
              context.startService(new Intent(context, 
              ShowNotificationService.class));
            }
     }
}



public class ShowNotificationService extends Service {

     @Override
     public void onCreate() {
          super.onCreate();
           String date_s = "2017-06-26 15:11:00";

           // *** note that it's "yyyy-MM-dd hh:mm:ss" not "yyyy-mm-dd hh:mm:ss"
            SimpleDateFormat dt = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
             Date date = null;
             try {
                 date = dt.parse(date_s);
              } catch (ParseException e) {
                  e.printStackTrace();
              }

              AgendarNotificacao(date);
         }

         @Override
         public IBinder onBind(Intent intent) {
              return null;
         }

private void AgendarNotificacao(Date data) {

    // Obtém um novo calendário e define a data para a data da notificação
    Calendar calendar = Calendar.getInstance();
    calendar.setTime(data);

    // Obtém um alarm manager
    AlarmManager alarmManager = (AlarmManager) getApplicationContext().getSystemService(getBaseContext().ALARM_SERVICE);

    // O id a ser usado no pending intent
    int id = (int) System.currentTimeMillis();

    // Prepare the intent which should be launched at the date
    Intent intent = new Intent(this, CriarNotificacao.class);

    // Obtém o pending intent
    PendingIntent pendingIntent = PendingIntent.getBroadcast(getApplicationContext(), id, intent, PendingIntent.FLAG_UPDATE_CURRENT);

    // Regista o alerta no sistema.
    alarmManager.set(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), pendingIntent);

}
}

public class CriarNotificacao extends BroadcastReceiver {
@TargetApi(Build.VERSION_CODES.JELLY_BEAN)
@Override
public void onReceive(Context context, Intent intent) {

    NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(context)
            .setContentTitle("lala")
            .setContentText("conteudo")
            .setAutoCancel(true);

    TaskStackBuilder stackBuilder = TaskStackBuilder.create(context);

    PendingIntent resultPendingIntent =
            stackBuilder.getPendingIntent(
                    0,
                    PendingIntent.FLAG_CANCEL_CURRENT
            );

    mBuilder.setContentIntent(resultPendingIntent);

    NotificationManager mNotificationManager = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);

    Vibrator vibrator = (Vibrator) context.getSystemService(Context.VIBRATOR_SERVICE);
    vibrator.vibrate(1500);

    mNotificationManager.notify(id, mBuilder.build());

}
}