Lollipop keyguard not dismissed?

I'm developing a app that in certain times it should wake up the device and dismiss the keyguard to display some activity until the user dismisses it. So, the

getWindow().addFlags(WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD |
                    WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED);

does not work on Android Lollipop, meanwhile it works perfectly on the pre Android versions !! Any suggestions?

This is the working solution:

BroadcastReceiver Class

@Override
public void onReceive(Context context, Intent intent) {
    mWakeLock = ((PowerManager) context.getApplicationContext().getSystemService(Context.POWER_SERVICE)).newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "TAG");
    if (!mWakeLock.isHeld()) {
        mWakeLock.acquire();
    }
    Intent intent = new Intent(context, MainActivity.class);
    intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    context.startActivity(intent);
    mWakeLock.release();
}

MainActivity Class

@Override
public void onCreate(Bundle bundle) {
    super.onCreate(bundle);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN |
                    WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD |
                    WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED |
                    WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON,
            WindowManager.LayoutParams.FLAG_FULLSCREEN |
                    WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD |
                    WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED |
                    WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON);
setContentView(R.layout.activity);
....
}

And now it is working even on Android Lollipop 5.0.1