C# kodunda hata var mı?

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 Aeron_Launcher
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void guna2Button1_Click(object sender, EventArgs e)
        {
            if (String.IsNullOrEmpty(guna2TextBox1.Text)) ;
            MessageBox.Show("You Can't enter the game without a username");
       
         else
                label2.Text = guna2TextBox1.Text;
                label2.Visible = true;
             guna2Button1.Visible = false;
        }
    }
}

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 Aeron_Launcher
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void guna2Button1_Click(object sender, EventArgs e)
        {
            if (String.IsNullOrEmpty(guna2TextBox1.Text))
            {
                MessageBox.Show("You Can't enter the game without a username");
            }
            else
            {
                label2.Text = guna2TextBox1.Text;
                label2.Visible = true;
                guna2Button1.Visible = false;
            }
        }
    }
}

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;
using System.Threading;
using CmlLib.Core;
using CmlLib.Core.Auth;
namespace Aeron_Launcher
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void guna2Button1_Click(object sender, EventArgs e)
        {
            if (String.IsNullOrEmpty(guna2TextBox1.Text))
            {
                MessageBox.Show("You cant enter the game without using name. Please Enter A user name");
            }

            else
            {


                label2.Text = guna2TextBox1.Text;
                label2.Visible = true;
                guna2Button1.Visible = true;



            }
            async private void gameoyunac();
            
        }

    }
}