Problems with ActionListener JAVA

Good I have a problem for a Java application for the Uni I am new to Java and I would like to ask for some help, it is a simple button to operate the division of two numbers and display them on the screen with a small check to show if that the user enters letters instead of numbers, but the buttons do not initiate the functions to which they are associated, here my code:

package graphics;

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;


public class PpalWindow extends JFrame implements ActionListener
{

/**
 * 
 */
private static final long serialVersionUID = 1L;
//ATTR's 
private Container cont;
private JPanel flowPanel, gridPanel;
private JButton operateButton, clearText;
private JLabel text1, text2, text3;
private JTextField field1,field2,field3;
private PpalWindow fatherFrame;

public  PpalWindow()
{
    this.cont = null;
    this.flowPanel= null;
    this.gridPanel = null;
    this.operateButton = null;
    this.clearText = null;
    this.text1 = null;
    this.text2 = null;
    this.text3 = null;
    this.field1= null;
    this.field2 = null;
    this.field3 = null;
    this.fatherFrame = null;


    //Inicializamos los componentes 
    makeFlowPanel();
    makeGridPanel();
    initializeComps();

}


// Método para hacer un set del atributo que guardará a este JFrame como el padre.
    public void setFatherFrame(PpalWindow pw) { PpalWindow pf = null;
    this.fatherFrame = pf; }





public void makeGridPanel()
{
    this.gridPanel= new JPanel();
    this.text1 = new JLabel("Distancia: ");
    this.text1.setFont(new Font("Arial",0,24));
    this.field1 = new JTextField(2);
    this.text2 = new JLabel("Tiempo: ");
    this.text2.setFont(new Font("Arial",0,24));
    this.field2 = new JTextField(2);
    this.text3 = new JLabel("Resultado: ");
    this.text3.setFont(new Font("Arial",0,24));
    this.field3 = new JTextField(2);

    GridLayout gl = new GridLayout(3,2,0,5);
    this.gridPanel.setLayout(gl);
    this.gridPanel.add(text1);
    this.gridPanel.add(field1);
    this.gridPanel.add(text2);
    this.gridPanel.add(field2);
    this.gridPanel.add(text3);
    this.gridPanel.add(field3);     
}

public void makeFlowPanel()
{
    this.flowPanel = new JPanel();
    this.operateButton = new JButton("Calcular");
    this.operateButton.setFont(new Font("Arial",0,18));
    this.clearText = new JButton("Borrar");
    this.clearText.setFont(new Font("Arial",0,18));
    this.flowPanel.setLayout(new FlowLayout());
    this.flowPanel.add(operateButton);
    this.flowPanel.add(clearText);

}
public void initializeComps() 
{
    this.setTitle("Calculo de velocidad de un  projectil");
    this.setResizable(false);
    this.setLocationRelativeTo(null);
    this.setSize(600, 200);
    cont= getContentPane();
    cont.setLayout(new BorderLayout());
    cont.add(this.gridPanel,BorderLayout.CENTER);
    cont.add(this.flowPanel,BorderLayout.SOUTH);

}

@Override
public void actionPerformed(ActionEvent e) 
{
    //Variables Locales 
     AlertWindow aw = null;
     double number1 = 0d;
     double number2 = 0d;
     int error = 0;

     // Exepcion para verificar si se ingresan numeros o letras en los campos 
     if (e.getSource()==this.clearText)
     {
         textClear();// Funcion que limpia los campos 
     }
     else if (e.getSource()==this.operateButton){
            try{
                    number1= Double.parseDouble(this.field1.getText());
                    number2 = Double.parseDouble(this.field2.getText());
               }
            catch(NumberFormatException nfe){ error = 1; }

            if(error !=0)
                {
                    // Instanciamos la ventana de alerta
                    aw = new AlertWindow(this.fatherFrame,true);
                    //asignamos el mensaje a mostrar 
                    if(error==1){aw.message.setText("Debe Ingresar Numero Reales"); }
                }
            else
                {
                    this.operate(number1,number2);
                }
         }

}

public void operate(double n1, double n2)
{
    // Variable local
    double result = 0d;
    result = n1/n2;
    this.field3.setText(" "+result);
}

public void textClear()
{
    this.field1.setText("");
    this.field2.setText("");
}
}

the AlertWindow window looks like this:

package graphics;

import java.awt.FlowLayout;

import javax.swing.JDialog;
import javax.swing.JLabel;
import javax.swing.JPanel;

import graphics.PpalWindow;

public class AlertWindow extends JDialog 
{
/**
 * 
 */
private static final long serialVersionUID = 1L;
JPanel panel;
JLabel message;

public AlertWindow(PpalWindow pw, boolean isModal)
{
    super(pw, isModal);
    this.setTitle("CUIDADO!");
    this.setSize(200, 100);
    this.setResizable(false);
    this.setLocationRelativeTo(null);
    this.panel = new JPanel();
    this.panel.setLayout(new FlowLayout());
    this.message = new JLabel();
}

public void AddComponents()
{
    this.panel.add(this.message);
    this.add(this.panel);
}
}

and the Main is like this:

package main;
import graphics.PpalWindow;
public class Projectil {

public static void main(String[] args) {

    PpalWindow pw = new PpalWindow();
    pw.setVisible(true);
}

}