信息显示不出来

Question

最近自己做勒个聊天工具
但是接收到的信息不能显示出来(用工具有截到信息)
希望大家给点意见和建议using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Net;
using System.Net.Sockets;
using System.IO;
using System.Threading;namespace WindowsApplication1
{
    public partial class Form1 : Form
    {
        TcpClient tcpClient = null;
        StreamWriter sw = null;
        StreamReader sr = null;
        Thread thConnection = null;
        Socket socket = null;
        TcpListener tcpListener = null;
        NetworkStream ns = null;
        string msg;
        StringBuilder sb = new StringBuilder();        public string Msg
        {
            get { return msg; }
            set { msg = value; }
        }        public Form1()
        {
            InitializeComponent();
        }        private void Form1_Load(object sender, EventArgs e)
        {
            tcpListener = new TcpListener(IPAddress.Any,5555);
            tcpListener.Start();
            thConnection = new Thread(new ThreadStart(WaitingConnection));
            thConnection.Start();
        }        private void WaitingConnection()
        { 
            while(true)
            {
                socket = tcpListener.AcceptSocket();
                if(ns==null)
                {
                    ns = new NetworkStream(socket);
                    sr = new StreamReader(ns);
                    sw = new StreamWriter(ns);
                }
            }
        }
        //用线程读取信息
        private void waitingMsg()
        {
            //this.textBox1 = new TextBox();
            while (true)
            {
                try
                {
                    this.Msg = sr.ReadToEnd();
                }
                catch (Exception e)
                {
                    MessageBox.Show(e.Message);
                }
            }
        }
        //开启连接
        private void btnConnection_Click(object sender, EventArgs e)
        {
            if(ns==null)
            {
                tcpClient = new TcpClient();
                tcpClient.Connect(IPAddress.Parse(this.txtIP.Text),5555);
                ns = tcpClient.GetStream();
                sw = new StreamWriter(ns);
                sr = new StreamReader(ns);
                Thread th = new Thread(new ThreadStart(waitingMsg));
                th.Start();
                timer1.Start();
                WaitConn.Start();
            }
        }
        //发送信息
        private void btnSend_Click(object sender, EventArgs e)
        {
            string sendmsg = textBox2.Text;
            try 
            {
                sw.Write(sendmsg);
                textBox2.Text = null;
                sw.Flush();
            }
            catch(Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }
        //定时的读取Msg里面的信息并显示
        private void timer1_Tick(object sender, EventArgs e)
        {
            if(this.Msg!=null)
            {
                sb.AppendLine(this.Msg);
                this.textBox1.Text = sb.ToString();
                this.msg = null;
            }
        }
        //保持连接
        private void WaitConn_Tick(object sender, EventArgs e)
        {
            sw.Write("   ");
            sw.Flush();
        }
    }
}