Ave, ho creato un codice che generi una finestra con sfondo ma nn mi visualizza il bottone. Dove sbaglio?

codice:
package din;

import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;


public class Main extends JFrame {

    String percorso = "./temp/1.jpg";
    File sfondo = new File(percorso);    
    
    public Main() throws IOException {

        BufferedImage image = ImageIO.read(sfondo);
        JLabel label = new JLabel(new ImageIcon(image));
        JFrame window = new JFrame("DIN");
        window.setSize(400,400);
        window.add(label);
           
        JButton bottone = new JButton("OK");        
        label.add(bottone);

        window.setVisible(true);
        window.addWindowListener(new WindowAdapter() {


            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });
    }

    public static void main(String[] args) throws IOException {
        Main principale = new Main();
    }
}