tcpllistener不确认连接

所以我正在编写一个简单的客户机-服务器应用程序。它应该发送一个数据包，然后等待接收一个数据包，然后发送一个等等……问题是，它收到了第一个数据包，但是当我在第二次迭代中启动TcpListener时，它给了我这个错误:

无法连接，因为目标机器处于活动状态127.0.0.1:13

private void listenForConnections()
    {
        bool prejelPaket = false; 
        listener = new TcpListener(IPAddress, port);
        listener.Start();
        while (!packetReceived)
        {
            try
            {
                client = listener.AcceptTcpClient();
                listener.Stop();
                networkStream = client.GetStream();
                byte[] message = new byte[1024];
                networkStream.Read(message, 0, message.Length);
                networkStream.Close();
                string strMessage = Encoding.UTF8.GetString(message);
                packetReceived= true;
                MessageBox.Show("received message: " + strMessage);
                client.Close();
            }
            catch (Exception ee)
            {
                thListen.Join();
            }
        }
    }
    private void sendPacket(object pClient)
    {
        string message = "test message;
        try
        {
            client = (TcpClient)pClient;
            client.Connect(IPAddress, port);
            networkStream = client.GetStream();
            byte[] strMessage = Encoding.UTF8.GetBytes(message);
            networkStream.Write(strMessage, 0, strMessage.Length);           
            networkStream.Close();
            client.Close();
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.ToString());
        }
    }

listener.Stop();