[SOLVED] Simple alignment problem with buttons - Libgdx

Newbie & Debugging Questions
#1

I have a settings window which I have buttons in it. Now , I want the buttons to be located at the center of the window but from some reason I can’t do that.

Here is my code:

toggleMusic = new ImageButton(menuSkin.getDrawable("musicon"));
		toggleSound = new ImageButton(menuSkin.getDrawable("soundon"));
        ImageButton quitSettingsButton = new ImageButton(menuSkin.getDrawable("close"));
        quitSettingsButton.addListener(new ClickListener() {
            @Override
            public void clicked(InputEvent event, float x, float y) {
                settingsWindow.remove();
            }
        });
        settingsWindow.getButtonTable().align(Align.center);
        settingsWindow.add(toggleMusic).size(100, 100).row();
        settingsWindow.add(toggleSound).size(100, 100).row();
        settingsWindow.add(quitSettingsButton).size(100, 100).row();

Here is an image of my window: