Unknown Error while Socket Programming

[escap3]

hey, how're you !?
buddies, I had a problem while creating a sample application which I recently downloaded from Micorosoft MSDN online library ...
here's is the picture of application :

http://www.turboimagehost.com/p/1817487/Error.JPG.html

and this is the source code :

using System;
using System.Collections.Generic;
using System.Text;
using System.Net;
using System.Net.Sockets;
namespace Socket_Baseed_Application
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.ForegroundColor = ConsoleColor.Green;
            TcpListener server = null;
            try
            {
                Int32 port = 3333;
                IPAddress localAddr = IPAddress.Parse("127.0.0.1");
                server = new TcpListener(localAddr, port);
                server.Start();
                Byte[] bytes = new Byte[256];
                string data = null;
                while (true)
                {
                    Console.WriteLine("waiting for a connection");
                    TcpClient client = server.AcceptTcpClient();
                    Console.WriteLine("Connected !");
                    data = null;
                    NetworkStream stream = client.GetStream();
                    int i;
                    while ((i=stream.Read(bytes,0,bytes.Length))!=0)
                    {
                        data = System.Text.Encoding.ASCII.GetString(bytes, 0, i);
                        Console.WriteLine("Recieved : {0}",data);
                        data = data.ToUpper();
                        byte[] msg = System.Text.Encoding.ASCII.GetBytes(data);
                        stream.Write(msg, 0, msg.Length);
                        Console.WriteLine("Sent : {0}",data);
                    }
                    client.Close();
                }

            }
            catch (SocketException e)
            {
                Console.WriteLine("Socket Exception : {0}", e);
            }
            finally
            {
                server.Stop();
            }
            Console.WriteLine("\nHit enter to continue ...");
            Console.Read();

        }
    }
}

I will really appreciate to one who can help me ...
unfortunately, every application that I create with this class has the same problem ...,

beforehand appreciate ...
thanks .