Hi, in these days i started to looking for a good sdk to combine with Vuforia.
I think this one is pretty good so i started to use, but i've encountered some problem.
Can someone help me?

I followed step by step this helpful guide: http://www.jpct.net/wiki/index.php/Integrating_JPCT-AE_with_Vuforia

But when I call the function updateCamera(), i have ever the same error:
This is my code:

  public ImageTargetsRenderer(ImageTargets activity){
    this.mActivity = activity;
    world = new World();
    world.setAmbientLight(20, 20, 20);

    sun = new Light(world);
    sun.setIntensity(250, 250, 250);

    // Create a texture out of the icon...:-)
    Texture texture = new Texture(BitmapHelper.rescale(BitmapHelper.convert(mActivity.getResources().getDrawable(R.drawable.ic_launcher)), 64, 64));
    TextureManager.getInstance().addTexture("texture", texture);

    cube = Primitives.getCube(10);
    cube.calcTextureWrapSpherical();
    cube.setTexture("texture");
    cube.strip();
    cube.build();
    cube.setCollisionMode(Object3D.COLLISION_CHECK_OTHERS|Object3D.COLLISION_CHECK_SELF);
cube.setCollisionOptimization(true);

    world.addObject(cube);

    cam = world.getCamera();
    //cam.moveCamera(Camera.CAMERA_MOVEOUT, 50);
    //cam.lookAt(cube.getTransformedCenter());

    SimpleVector sv = new SimpleVector();
    sv.set(cube.getTransformedCenter());
    sv.y -= 100;
    sv.z -= 100;
    sun.setPosition(sv);
    MemoryHelper.compact();

    }

    /** Native function for initializing the renderer. */
    public native void initRendering();

    /** Native function to update the renderer. */
    public native void updateRendering(int width, int height);

    /** Called when the surface is created or recreated. */
    public void onSurfaceCreated(GL10 gl, EGLConfig config)
    {
        DebugLog.LOGD("GLRenderer::onSurfaceCreated");

        // Call native function to initialize rendering:
        initRendering();

        // Call QCAR function to (re)initialize rendering after first use
        // or after OpenGL ES context was lost (e.g. after onPause/onResume):
        QCAR.onSurfaceCreated();
    }


    /** Called when the surface changed size. */
    public void onSurfaceChanged(GL10 gl, int width, int height)
    {
    DebugLog.LOGD("GLRenderer::onSurfaceChanged");

    // Call native function to update rendering when render surface
    // parameters have changed:
    updateRendering(width, height);

    // Call QCAR function to handle render surface size changes:
    QCAR.onSurfaceChanged(width, height);

    if (fb != null) {
    fb.dispose();
    }
    fb = new FrameBuffer(width, height);
    }


    /** The native render function. */
    public native void renderFrame();


    /** Called to draw the current frame. */
    public void onDrawFrame(GL10 gl)
    {
        if (!mIsActive)
            return;
       
        // Update render view (projection matrix and viewport) if needed:
        mActivity.updateRenderView();

        // Call our native function to render content
        renderFrame();
       
        updateCamera();
       
        world.renderScene(fb);
        world.draw(fb);
        fb.display();
       
    }
   
    public void updateModelviewMatrix(float mat[]) {
        modelViewMat = mat;
    }
   
    public void updateCamera() {
    Matrix m = new Matrix();
    m.setDump(modelViewMat);
        cam.setBack(m);
    }


and this is my logcat:

04-23 13:24:50.255: E/AndroidRuntime(13001): FATAL EXCEPTION: GLThread 14
04-23 13:24:50.255: E/AndroidRuntime(13001): java.lang.NullPointerException
04-23 13:24:50.255: E/AndroidRuntime(13001): at com.threed.jpct.Matrix.setDump(Matrix.java:955)
04-23 13:24:50.255: E/AndroidRuntime(13001): at com.example.vuforiajpctae.ImageTargetsRenderer.updateCamera(ImageTargetsRenderer.java:160)
04-23 13:24:50.255: E/AndroidRuntime(13001): at com.example.vuforiajpctae.ImageTargetsRenderer.onDrawFrame(ImageTargetsRenderer.java:146)
04-23 13:24:50.255: E/AndroidRuntime(13001): at android.opengl.GLSurfaceView$GLThread.guardedRun(GLSurfaceView.java:1388)
04-23 13:24:50.255: E/AndroidRuntime(13001): at android.opengl.GLSurfaceView$GLThread.run(GLSurfaceView.java:1138)


the problem is about the function setDump in updateCamera, but i don't know how to fix, i tryed everything...
Please, healp me!