[VB.NET] Keine Fehlermeldung - TCP/IP

Imports System.Net.Sockets
Imports System.Threading
Imports System.IO

Public Class Form1
    Dim listener As New TcpListener(55555)
    Dim Client As TcpClient
    Dim message As String = ""

    Private Sub listening()
        listener.Start()
    End Sub

    Private Sub Form1_FormClosing(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
        listener.Stop()
    End Sub

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim listthread As New Thread(New ThreadStart(AddressOf listening))
        listthread.Start()
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Client = New TcpClient(TextBox1.Text, 55555)
        Dim Writer As New StreamWriter(Client.GetStream())
        Writer.Write(TextBox3.Text)
        Writer.Flush()
    End Sub

    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        If listener.Pending = True Then
            message = ""
            Client = listener.AcceptTcpClient

            Dim reader As New StreamReader(Client.GetStream)
            While reader.Peek < -1
                message = message + Convert.ToChar(reader.Read()).ToString
            End While
            TextBox2.Text = TextBox2.Text & message & vbCrLf
        Else : End If
    End Sub
End Class