Режим киоска не работает.?

Я создаю пример приложения с режимом киоска в своем приложении, чтобы проверить, работает ли режим киоска или нет.?. Но в примере приложения режим киоска не работает. Я имею в виду, что после того, как экран погаснет, активность не запускается.

Я взял это из [http://www.andreas-schrade.de/2015/02/16/android-tutorial-how-to-create-a-kiosk-mode-in-android/][здесь]

это моя основная деятельность

public class MainActivity extends Activity{

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    getWindow().addFlags(WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD);
    setContentView(R.layout.activity_main);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}
@Override
public void onWindowFocusChanged(boolean hasFocus) {
  super.onWindowFocusChanged(hasFocus);
  if(!hasFocus) {
      // Close every kind of system dialog
    Intent closeDialog = new Intent(Intent.ACTION_CLOSE_SYSTEM_DIALOGS);
    sendBroadcast(closeDialog);
   }
 }
}

Это мой класс приложения

public class AppContext extends Application {

  private AppContext instance;
  private PowerManager.WakeLock wakeLock;
  private OnScreenOffReceiver onScreenOffReceiver;
  PowerManager pm;

  @Override
  public void onCreate() {
    super.onCreate();
    instance = this;
    registerKioskModeScreenOffReceiver();
     pm = (PowerManager) getSystemService(Context.POWER_SERVICE);
     startKioskService();
  }

  private void registerKioskModeScreenOffReceiver() {
    // register screen off receiver
    final IntentFilter filter = new IntentFilter(Intent.ACTION_SCREEN_OFF);
    onScreenOffReceiver = new OnScreenOffReceiver();
    registerReceiver(onScreenOffReceiver, filter);
  }

  public PowerManager.WakeLock getWakeLock() {
    if(wakeLock == null) {
      // lazy loading: first call, create wakeLock via PowerManager.

      wakeLock = pm.newWakeLock(PowerManager.FULL_WAKE_LOCK | PowerManager.ACQUIRE_CAUSES_WAKEUP, "wakeup");
    }
    return wakeLock;
  }
  private void startKioskService() { // ... and this method
      startService(new Intent(this, KioskService.class));
    }
}

Это класс приемника

public class OnScreenOffReceiver extends BroadcastReceiver {
  private static final String PREF_KIOSK_MODE = "pref_kiosk_mode";

  @Override
  public void onReceive(Context context, Intent intent) {
    if(Intent.ACTION_SCREEN_OFF.equals(intent.getAction())){
      AppContext ctx = (AppContext) context.getApplicationContext();
      // is Kiosk Mode active?
      if(isKioskModeActive(ctx)) {
        wakeUpDevice(ctx);
      }
    }
  }

  private void wakeUpDevice(AppContext context) {
    PowerManager.WakeLock wakeLock = context.getWakeLock(); // get WakeLock reference via AppContext
    if (wakeLock.isHeld()) {
      wakeLock.release(); // release old wake lock
    }

    // create a new wake lock...
    wakeLock.acquire();

    // ... and release again
    wakeLock.release();
  }

  private boolean isKioskModeActive(final Context context) {
    SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(context);
    return sp.getBoolean(PREF_KIOSK_MODE, false);
  }


}

Это класс обслуживания

public class KioskService extends Service {

  private static final long INTERVAL = TimeUnit.SECONDS.toMillis(2); // periodic interval to check in seconds -> 2 seconds
  private static final String TAG = KioskService.class.getSimpleName();
  private static final String PREF_KIOSK_MODE = "pref_kiosk_mode";

  private Thread t = null;
  private Context ctx = null;
  private boolean running = false;

  @Override
  public void onDestroy() {
    Log.i(TAG, "Stopping service 'KioskService'");
    running =false;
    super.onDestroy();
  }

  @Override
  public int onStartCommand(Intent intent, int flags, int startId) {
    Log.i(TAG, "Starting service 'KioskService'");
    running = true;
    ctx = this;

    // start a thread that periodically checks if your app is in the foreground
    t = new Thread(new Runnable() {
      @Override
      public void run() {
        do {
          handleKioskMode();
          try {
            Thread.sleep(INTERVAL);
          } catch (InterruptedException e) {
            Log.i(TAG, "Thread interrupted: 'KioskService'");
          }
        }while(running);
        stopSelf();
      }
    });

    t.start();
    return Service.START_NOT_STICKY;
  }

  private void handleKioskMode() {
    // is Kiosk Mode active? 
      if(isKioskModeActive(ctx)) {
        // is App in background?
      if(isInBackground()) {
        restoreApp(); // restore!
      }
    }
  }

  private boolean isInBackground() {
    ActivityManager am = (ActivityManager) ctx.getSystemService(Context.ACTIVITY_SERVICE);

    List<ActivityManager.RunningTaskInfo> taskInfo = am.getRunningTasks(1);
    ComponentName componentInfo = taskInfo.get(0).topActivity;
    return (!ctx.getApplicationContext().getPackageName().equals(componentInfo.getPackageName()));
  }

  private void restoreApp() {
    // Restart activity
    Intent i = new Intent(ctx, MainActivity.class);
    i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    ctx.startActivity(i);
  }

  public boolean isKioskModeActive(final Context context) {
    SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(context);
    return sp.getBoolean(PREF_KIOSK_MODE, false);
  }

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

это мой манифест

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.kioskmode"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
    android:minSdkVersion="8"
    android:targetSdkVersion="21" />

<application
    android:allowBackup="true"
    android:name=".AppContext"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name=".MainActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <service android:name="com.example.kioskmode.KioskService" android:exported="false"></service>
    <receiver android:name="com.example.kioskmode.OnScreenOffReceiver" android:enabled="true" >
        <intent-filter android:priority="1000" >
            <action android:name="android.app.action.SCREEN_OFF" />
            <action android:name="android.app.action.SCREEN_ON" />
        </intent-filter>
    </receiver>        
</application>
    <uses-permission android:name="android.permission.GET_TASKS"/>
    <uses-permission android:name="android.permission.WAKE_LOCK" />
    <uses-permission android:name="android.permission.READ_PHONE_STATE" />
    <uses-permission       android:name="android.permission.RECEIVE_BOOT_COMPLETED" />

</manifest>

Любой может решить это... для меня..?? Заранее спасибо..