Не работают примеры из книги "Эндрю Стиллмен, Грин - Изучаем c#"

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
 
namespace game
{
    public partial class Form1 : Form
    {
        Guy joe;
        Guy bob;
        int bank = 100;
 
        public Form1()
        {
            InitializeComponent();
 
            bob = new Guy();
            bob.Name = "Bob";
            bob.Cash = 100;
 
            joe = new Guy();
            joe.Name = "Joe";
            joe.Cash = 50;
 
            UpdateForm();
        }
 
        public void UpdateForm()
        {
            joesCashLabel.Text = joe.Name + " has $" + joe.Cash;
            bobsCashLabel.Text = bob.Name + " has $" + bob.Cash;
            bankCashLabel.Text = " bank have now $" + bank;
        }
 
            private void button1_Click(object sender, EventArgs e)
        {
            if (bank >= 10)
            {
                bank -= joe.ReceiveCash(10);
                UpdateForm();
 
            }else
            {
                MessageBox.Show("In bank has not money.");
 
            }
        }
 
        private void button2_Click(object sender, EventArgs e)
        {
            bank += bob.GiveCash(5);
            UpdateForm();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using System.Windows.Forms;
 
namespace game
{
    static class Guy
    {
        public string Name;
        public int Cash;
 
        public int GiveCash(int amount)
        {
            if (amount<=Cash && amount >0)
            {
                Cash -= amount;
                return amount;
            }
            else
            {
                                MessageBox.Show(
                                    "У меня не хватает денег " +amount, Name + " говорит..." );
                return 0;
 
            }
        }
 
        public int ReceiveCash(int amount)
        {
            if(amount > 0)
            {
                Cash += amount;
                return amount;
            }else
            {
                MessageBox.Show(amount + " мне не нужно", Name + " говорит...");
                return 0;
            }
        }
 
        /// <summary>
        ///
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new Form1());
        }
    }
}