JAVA代码查错：菜单项属性?报错

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

public class Test extends JFrame {

    Game game;

    JMenuBar bar = new JMenuBar();
    JMenu  menu1 = new JMenu("游戏");
    JMenuItem   menuItem11 = new JMenuItem("开始");
 
    public Test() {
        setSize(500, 500);          
        Menu(); 
       
        Container container = getContentPane();
        container.setBackground(Color.black); 
        game=new Game();
        container.add(game);
       
        setLocationRelativeTo(null);
        setResizable(false);
        setVisible(true);
    }

    private void Menu() {
        bar.add(menu1);
        menu1.add(menuItem11);
        setJMenuBar(bar);

        menuItem11.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                game.play();
                menuItem11.setEnabled(false);   // “开始”菜单项  变灰失效
            }
        });
    }

    public static void main(String[] args) {
        new Test() ;
    }

}

// Game 类
class Game extends JPanel implements Runnable {
 Thread thread;

 public void play() {
  thread = new Thread(this);
  thread.start();
 }

 public void run() {
  System.out.println("已执行！");
  stop();
 }

 public void stop() {
  thread.stop();
  menuItem11.setEnabled(true);   // 要求“开始”变为正常
 }

}

这句报错：
menuItem11.setEnabled(false);   // “开始”菜单项  变灰失效

错误类型：menuItem11 cannot be resolved