Keine antwort von serialport

Hallo,

kann mit jemand sagen warum VB die Antwort vom Handz nicht rausgibt ?
wo ist mein fehler?

Imports System.IO

Public Class Form1

 Dim WithEvents serialport As New IO.Ports.SerialPort

 Private Sub Form1\_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
 For i As Integer = 0 To My.Computer.Ports.SerialPortNames.Count - 1
 ListBox1.Items.Add(My.Computer.Ports.SerialPortNames(i))
 Next
 Button2.Enabled = False
 End Sub

 Private Sub Button1\_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
 If serialport.IsOpen Then
 serialport.Close()

 End If
 Try
 With serialport
 .PortName = ListBox1.Text
 .BaudRate = 115200
 .Parity = Ports.Parity.None
 .DataBits = 8
 .StopBits = Ports.StopBits.One
 End With
 serialport.Open()
 Button1.Enabled = False

 Catch ex As Exception
 MsgBox(ex.ToString)
 End Try
 End Sub

 Private Sub Button3\_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
 Try
 serialport.Write("AT+CSQ" & vbCrLf)
 With txtdatareceived

 .appendtext(txtdatatosend.text & vbCrLf)
 End With
 txtdatatosend.text = String.Empty
 Catch ex As Exception
 MsgBox(ex.ToString)
 End Try
 End Sub

 Private Sub SerialPort1\_DataReceived(ByVal sender As Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived
 MsgBox("da kommt was")

 End Sub
End Class

\>Imports System.IO

Public Class Form1

 Dim WithEvents serialport As New IO.Ports.SerialPort

 Private Sub Form1\_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
 For i As Integer = 0 To My.Computer.Ports.SerialPortNames.Count - 1
 ListBox1.Items.Add(My.Computer.Ports.SerialPortNames(i))
 Next
 Button2.Enabled = False
 End Sub

 Private Sub Button1\_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
 If serialport.IsOpen Then
 serialport.Close()

 End If
 Try
 With serialport
 .PortName = ListBox1.Text
 .BaudRate = 115200
 .Parity = Ports.Parity.None
 .DataBits = 8
 .StopBits = Ports.StopBits.One
 End With
 serialport.Open()
 Button1.Enabled = False

 Catch ex As Exception
 MsgBox(ex.ToString)
 End Try
 End Sub

 Private Sub Button3\_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
 Try
 serialport.Write("AT+CSQ" & vbCrLf)
 With txtdatareceived

 .appendtext(txtdatatosend.text & vbCrLf)
 End With
 txtdatatosend.text = String.Empty
 Catch ex As Exception
 MsgBox(ex.ToString)
 End Try
 End Sub

 Private Sub SerialPort1\_DataReceived(ByVal sender As Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived
 MsgBox("da kommt was")

 End Sub
End Class