My App always show "Hello World"

Hi I'm new in Android Developing.

I want to create an easy game using AndEngine. So I wanted to try a little sample. But when i deploy the apk-file to my nexus7. But when I run the App, it always says "Hello World" in the center of screen with White Background. But it should show an Image with specific Background Color.

Here's my code:

public class MainActivity extends SimpleBaseGameActivity {
private static final float CAMERA_WIDTH = 720;
private static final float CAMERA_HEIGHT = 480;
private Camera mCamera;
private BitmapTextureAtlas mBitmapTextureAtlas;
private Engine mEngine;
private TextureRegion mFaceTextureRegion;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
}

@Override
public EngineOptions onCreateEngineOptions() {

    this.mCamera = new Camera(0, 0, CAMERA_WIDTH, CAMERA_HEIGHT);

    return new EngineOptions(true,
            ScreenOrientation.LANDSCAPE_FIXED, new RatioResolutionPolicy(
                    CAMERA_WIDTH, CAMERA_HEIGHT), mCamera);
}

@Override
protected void onCreateResources() {

    this.mBitmapTextureAtlas = new BitmapTextureAtlas(
            mEngine.getTextureManager(), 32, 32,
            TextureOptions.BILINEAR_PREMULTIPLYALPHA);

    BitmapTextureAtlasTextureRegionFactory.setAssetBasePath("gfx/");

    this.mFaceTextureRegion = BitmapTextureAtlasTextureRegionFactory
            .createFromAsset(this.mBitmapTextureAtlas, this,
                    "face_box.png", 0, 0);

    getTextureManager().loadTexture(this.mBitmapTextureAtlas);
}

@Override
protected Scene onCreateScene() {

    this.mEngine.registerUpdateHandler(new FPSLogger());
    final Scene scene = new Scene();
    scene.setBackground(new Background(new Color(0, 255, 128)));
    final int centerX = (int) ((CAMERA_WIDTH - this.mFaceTextureRegion
            .getWidth()) / 2);
    final int centerY = (int) ((CAMERA_HEIGHT - this.mFaceTextureRegion
            .getHeight()) / 2);
    final Sprite face = new Sprite(centerX, centerY,
            this.mFaceTextureRegion, new VertexBufferObjectManager());
    scene.attachChild(face);

    return scene;
}

}

What am I doing wrong? Thanks in advance.

Since you are using AndEngine SimpleBaseGameActivity, you don't need this

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
}

"Hello world" shows up because you are setting the content view, remove the override to onCreate and it should work.