Basic C# App to Demo Threading Not working

using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;
using System.Threading;

namespace Streams
{
    static class Program
    {
        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]

        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new Form1());
        }
    }
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;
using System.Threading;

namespace Streams
{
    public partial class Form1 : Form
    {
        FileStream fs;
        byte[] fileContents;
        AsyncCallback callback;

        public void syncRead()
        {
            OpenFileDialog ofd = new OpenFileDialog();
            ofd.ShowDialog();
            FileStream fs;
            try
            {
                fs = new FileStream(ofd.FileName, FileMode.OpenOrCreate);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
                return;
            }
            fs.Seek(0, SeekOrigin.Begin);
            byte[] fileContents = new byte[fs.Length];
            fs.Read(fileContents, 0, (int)fs.Length);
            tbResults.Text = Encoding.UTF8.GetString(fileContents);
            fs.Close();
        }

        public Form1()
        {
            InitializeComponent();
        }
        private void fs_StateChanged(IAsyncResult asyncResult)
        {
            if (asyncResult.IsCompleted)
            {
                tbResults.Text = Encoding.UTF8.GetString(fileContents);
                fs.Close();
            }
        }
        private void btnReadAsync_Click(object sender, EventArgs e)
        {
            openFileDialog.ShowDialog();
            callback = new AsyncCallback(fs_StateChanged);
            fs = new FileStream(openFileDialog.FileName, FileMode.Open,
            FileAccess.Read, FileShare.Read, 4096, true);
            fileContents = new Byte[fs.Length];
            fs.BeginRead(fileContents, 0, (int)fs.Length, callback, null);
        }

        private void btnReadSync_Click(object sender, EventArgs e)
        {
            Thread thdSyncRead = new Thread(new ThreadStart(syncRead));
            thdSyncRead.Start();
        }
    }
}