need simple help.....

Im confused why this isnt working....

Any ideas? What have I stupidly missed?

Thanks,
Peter

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import javax.swing.*;
import java.awt.*;
import java.util.*;

public class CAS2_Interface extends JPanel{

    CAS_Engine theCAS_Engine;

    public static void main(String[] args)
    {
        JFrame mainWindow = new JFrame("CASAT - Connect a Square on a
Tesseract (Multiplayer)");

        JPanel content = new JPanel();
        content.add(new CAS2_Interface(), BorderLayout.WEST);

        mainWindow.setContentPane(content);

        mainWindow.getContentPane().setBackground(new
Color(176,196,222));
        mainWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        mainWindow.setLocationRelativeTo(null);
        mainWindow.pack();
        mainWindow.setVisible(true);
    }

    public void CAS2_Interface()
    {
        setPreferredSize(new Dimension(600,471));
        setBackground(new Color(173,216,230));
    }

    public void paintComponent(Graphics g)
    {
        super.paintComponent(g);
        drawScreen((Graphics2D) g);
    }

    public void drawScreen(Graphics2D g)
    {
        //Uses the game board as defined in the program specification
        Image image = Toolkit.getDefaultToolkit().getImage("./
map.png");
        g.drawImage(image, 0,0,this);
    }
}