It is always easier for somebody to diagnose your problem if you include
your code.  So all I can do is give you an example of how to add a
MouseListener to a JPanel.  Don't forget that BorderLayout will cause
your component to expand to the size of your container.  I usually only
use BorderLayout when I have one component to add to the container.

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

public class test {
    public static void createGUI() {
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JPanel p = new JPanel();
        p.setBackground(Color.BLUE);
        p.addMouseListener(new MouseAdapter() {
            public void mousePressed(MouseEvent me) {
                System.out.println(me.getX()+" "+me.getY());
            }
        });
        f.add(p,BorderLayout.CENTER);
        f.setSize(640,480);
        f.setVisible(true);
    }

    public static void main(String[] args) {
        Runnable r = new Runnable() {
            public void run() {
                createGUI();
            }
        };
        EventQueue.invokeLater(r);
    }
}