vb.net HttpRequest

Option Strict On
Option Explicit On

Imports System.IO
Imports System.Net
Imports System.Text




Public Class Form1
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

      
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdLogin.Click
        Dim cookieCon As New CookieContainer
        Dim request As HttpWebRequest = DirectCast(HttpWebRequest.Create("http://www.bananenkoenig.de/index.php?ac=login"), HttpWebRequest)

        request.Method = "POST"
        request.CookieContainer = cookieCon
        request.UserAgent = "Mozilla/6.0 (Windows NT 6.2; WOW64; rv:16.0.1) Gecko/20121011 Firefox/16.0.1"
        request.ContentType = "application/x-www-form-urlencoded"
        Dim post As String = "selserver=Plantage%A01&user=testuser&password=testuser&x=172&y=8"
        Dim byteArr() As Byte = Encoding.UTF8.GetBytes(post)
        request.ContentLength = byteArr.Length
        Dim dataStream As Stream = request.GetRequestStream()
        dataStream.Write(byteArr, 0, byteArr.Length)
        Dim response As HttpWebResponse = DirectCast(request.GetResponse(), HttpWebResponse)
        Dim reader As New StreamReader(response.GetResponseStream())
        Dim seitenQuelltext As String = reader.ReadToEnd

        If seitenQuelltext.Contains("Logout") Then
            MsgBox("Fine")

        Else
            MsgBox("Not Fine")

        End If



    End Sub
End Class