Vuforia init Camera

Hi 

I'm a android developer and I want to use Vuforia library, but I can't init camera device to detect and show 3D object. I use this code but this don't work :

Render myRenderer;     public RajawaliSurfaceView rajawaliSurface;

    @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.layout_main);

        rajawaliSurface = (RajawaliSurfaceView) findViewById(R.id.rajawali_surface);         rajawaliSurface.setFrameRate(60);         rajawaliSurface.setRenderMode(IRajawaliSurface.RENDERMODE_WHEN_DIRTY);         rajawaliSurface.setTransparent(true);         rajawaliSurface.setBackgroundColor(Color.WHITE);         myRenderer = new Render(this);         rajawaliSurface.setSurfaceRenderer(myRenderer);

    }

please Help me.

Thanks