Libgdx background image change

I want to change the background image of the menu every x-seconds. I am using libGDX scene2D.ui to create a menu. The TestScreen class extends AbstractScreen, which is an abstract class that implements the Screen class for the libGDX library. Problem. After loading the image onto the scene through the table object in the stack, changing the link to the image to another image does nothing. Stage.draw () does not give any worries, as if it made a copy of my original image. I would like to save the background as an image class and render through stage.draw ().

To complicate matters even further, if I changed the image to another in the render () method, then the image.setVisible (false) function also stops working.

public class TestScreen extends AbstractScreen {

private Stage stage;
private Image background;
private boolean ChangeBackground = true;
private final float refreshTime = 2.0f; // refresh to new image every 2 seconds.
private float counter = refreshTime;

public TestScreen(Game game) {
    super(game);
}

@Override
public void render(float deltaTime) {
    Gdx.gl.glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
    Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT);

    if(ChangeBackground){
        counter -= deltaTime;
        if(counter < 0){
            counter = refreshTime;
            // Assets class has the 12 images loaded as "Image" objects already.
            // I simple want to change the reference to other (already loaded in memory images) ...
            // and make stage render the new image.
            background = Assets.instance.wallpapers[(int) (Math.random()*12)];  // The image should change.
            //background.setVisible(false);
        }
    }
    stage.act(deltaTime);
    stage.draw();
}

@Override
public void resize(int width, int height) {
    stage.setViewport(Constants.VIEWPORT_GUI_WIDTH, Constants.VIEWPORT_GUI_HEIGHT, false);
}
@Override
public void show() {
    stage = new Stage();
    Gdx.input.setInputProcessor(stage);
    makeStage();
}
@Override
public void hide() {
    stage.dispose();
}
@Override
public void pause() {   
}

// Builds the Background later and adds it to a stage through a stack.
// This is how it done in my game. I made this test bench to demonstrate.
private void makeStage() {
    Table BackGroundLayer = new Table();
    background = Assets.instance.wallpapers[(int) (Math.random()*12)];
    BackGroundLayer.add(background);

    Stack layers = new Stack();
    layers.setSize(800, 480);
    layers.add(BackGroundLayer);

    stage.clear();
    stage.addActor(layers);
}

}