Set 0, 0 to top left

I am trying to set up an ortho view with 0, 0 in the top left using this code:


        GameStateManager.create();
        TankGameState currentState = new TankGameState(display);
        currentState.setActive(true);
        GameStateManager.getInstance().attachChild(currentState);
        cam = display.getRenderer().createCamera(display.getWidth(), display.getHeight());
        cam.setParallelProjection( true );
        cam.setFrustum( -10, 10, 0, 800, 0, 600);
//        cam.setViewPort(0, 1, 1, 0);
//        Vector3f loc = new Vector3f( 0.0f, 0.0f, 1.0f );
//        Vector3f left = new Vector3f( -1.0f, 0.0f, 0.0f );
//        Vector3f up = new Vector3f( 0.0f, 1.0f, 0.0f );
//        Vector3f dir = new Vector3f( 0.0f, 0f, -1.0f );
//        /** Move our camera to a correct place and orientation. */
//        cam.setFrame( loc, left, up, dir );
        /** Signal that we've changed our camera's location/frustum. */
        cam.update();
        /** Assign the camera to this renderer. */
        display.getRenderer().setCamera( cam );

I have tried to do it with setFrustrum(), setViewPort() and set the camera attributes. None of them change anything. 0, 0 remains at the bottom left of the screen. I tried to search to see if anyone had a similar problem, but couldn’t find anything. Can anyone tell me what I am missing?