Click JPanel does not work

I'm creating an interface for a system and would like it when the user clicked on a JPanel , open another window. The program is compiled normally, but by the time I click on JPanel , it does not open the desired window and exceptions are thrown:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at javax.swing.ImageIcon.<init>(ImageIcon.java:217)
at telas.Venda.initComponents(Venda.java:66)
at telas.Venda.<init>(Venda.java:22)
at telas.TelaProprietario.vendaMouseClicked(TelaProprietario.java:935)
at telas.TelaProprietario.access$2400(TelaProprietario.java:15)
at telas.TelaProprietario$13.mouseClicked(TelaProprietario.java:616)
at java.awt.Component.processMouseEvent(Component.java:6536)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
at java.awt.Component.processEvent(Component.java:6298)
at java.awt.Container.processEvent(Container.java:2236)
at java.awt.Component.dispatchEventImpl(Component.java:4889)
at java.awt.Container.dispatchEventImpl(Container.java:2294)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4888)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4534)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4466)
at java.awt.Container.dispatchEventImpl(Container.java:2280)
at java.awt.Window.dispatchEventImpl(Window.java:2746)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:90)
at java.awt.EventQueue$4.run(EventQueue.java:731)
at java.awt.EventQueue$4.run(EventQueue.java:729)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

I created the interface through NetBeans. Below is part of the code:

package telas;

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

public class TelaProprietario extends javax.swing.JFrame
{
public TelaProprietario()
{
    initComponents();
}

private void initComponents()
{
    tela=new javax.swing.JPanel();
    venda=new javax.swing.JPanel();

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
    setExtendedState(JFrame.MAXIMIZED_BOTH);
    setMinimumSize(new java.awt.Dimension(1024,768));

    tela.setBackground(new java.awt.Color(204,204,255));
    tela.setMinimumSize(new java.awt.Dimension(1024,768));
    tela.setPreferredSize(new java.awt.Dimension(1024,768));

    venda.setBackground(new java.awt.Color(204,204,255));
    venda.setPreferredSize(new java.awt.Dimension(150,150));
    venda.addMouseListener(new java.awt.event.MouseAdapter()
    {
        public void mouseClicked(java.awt.event.MouseEvent evt)
        {
            vendaMouseClicked(evt);
        }
        public void mouseEntered(java.awt.event.MouseEvent evt)
        {
            vendaMouseEntered(evt);
        }
        public void mouseExited(java.awt.event.MouseEvent evt)
        {
            vendaMouseExited(evt);
        }
    });

    // código de layout
}

private void vendaMouseEntered(java.awt.event.MouseEvent evt)
{
    venda.setBackground(new Color(255, 255, 255));
}

private void vendaMouseExited(java.awt.event.MouseEvent evt)
{
    venda.setBackground(new Color(204, 204, 255));
}

private void vendaMouseClicked(java.awt.event.MouseEvent evt)
{
    new Venda().setVisible(true); // outra tela
    setVisible(false);
}

public static void main(String args[])
{
    java.awt.EventQueue.invokeLater(new Runnable()
    {
        public void run()
        {
            new TelaProprietario().setVisible(true);
        }
    });
}

private javax.swing.JPanel tela;
private javax.swing.JPanel venda;
}

I would like to know what is causing this problem and how to resolve it.