Wakelock only working with usb-cable connected

Question

I have a rather odd problem. Lately i tried to use a wakelock in my application using the following code:

    /** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    PowerManager pm = (PowerManager) getSystemService(POWER_SERVICE);
    screenLock = pm.newWakeLock(PowerManager.FULL_WAKE_LOCK, "DoNotDimScreen");
    button = (Button)findViewById(R.id.button);
    button.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View view) {
            System.out.println("Clicked");
            try {
                Thread.sleep(5000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            if (!locked)
                setKeepScreenOn(WakeupLightActivity.this, true);
            else setKeepScreenOn(WakeupLightActivity.this, false);
            System.out.println("Screen will stay on");
        }
    });
}

public void setKeepScreenOn(Activity activity, boolean keepScreenOn) {
    if(keepScreenOn) {                    
        activity.getWindow().addFlags(WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON);          
        activity.getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
        this.screenLock.acquire();
    } 
    else {                                 
       activity.getWindow().clearFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);             
       activity.getWindow().clearFlags(WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON);
        this.screenLock.release();
    }
}

The wakelock works perfectly: 5 seconds after pressing the button (and locking my phone) the screen turns on. This test, however, was done while my phone was connected to my laptop for debugging using a USB cable.

Now comes the weird part. When I DON'T have my phone connected with the USB cable, the wakelock simply DOES NOT turn on the screen. The device I am using is an HTC desire. I have actually tested it on another HTC desire, which did the same thing. Next, i tried it on an HTC Desire HD. And guess what: It worked perfectly again! I am really confused about this and wondering if the problem is simply a flaw in my phone type, or if I am doing something wrong in my code. Is there anything I can do about it? It would be incredibly awkward if any potential customers with a malfunctioning phone type would encounter the same problem after having purchased my app.

Note that I also tried the application while charging my phone with the cable connected to a wall plug. This leads to the same problem as not having my phone connected at all. Both HTC Desires run the same Android version (2.2.2).

Answer 1

Apparently all of this occured simply because i was using the wrong flags. The problem was solved by creating the WakeLock with the following flags:

PowerManager.SCREEN_BRIGHT_WAKE_LOCK|PowerManager.ACQUIRE_CAUSES_WAKEUP