Very basic VB.Net & Serial IO issue

After searching around I am still having issues with reading data from a serial port in VB.Net/VS2010. I know the Serial Port works, I can write to the port fine but when reading from it, nothing happens. I have only been programming for the last 3 weeks so am still trying to get my head around it all.

The program must run to capture data from a door logger, I will then be outputting the data to a database (not yet implemented - I want to get this part sorted first). I have tried using several terminal programs as well as another device which outputs data onto the serial line, with nothing displaying in the textbox tbxIn.

Any help would be greatly appreciated.

Code is below:

Imports System.IO.Ports
Imports System.IO.Ports.SerialPort

Public Class Form1

Dim comPort As IO.Ports.SerialPort = Nothing
Dim sComPort As String = ""
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    GetSerialPortNames()
End Sub

Sub GetSerialPortNames()
    ' Show all available COM ports.
    For Each sp As String In My.Computer.Ports.SerialPortNames
        lstPorts.Items.Add(sp)
    Next
End Sub


Private Sub lstPorts_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles lstPorts.SelectedIndexChanged
    sComPort = lstPorts.SelectedItem
    Button1.Enabled = True
End Sub

Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    ' Open the serial port using the OpenSerialPort method
    Button1.Enabled = False
    Button2.Enabled = True

    Try
        comPort = My.Computer.Ports.OpenSerialPort(sComPort, 9600, IO.Ports.Parity.None, 8, 1)
        ' comPort.DtrEnable = True
        comPort.ReadTimeout = 500
        Do
            comPort.WriteLine("Go")
            Dim sIncomming As String = comPort.ReadLine()

            tbxIn.Text = sIncomming & vbCrLf
        Loop
    Catch ex As TimeoutException
        tbxIn.Text &= "Error: Serial Port Read Timeout" & vbCrLf
    End Try

End Sub

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
    comPort.Close()
    Button1.Enabled = True
    Button2.Enabled = False
End Sub

Private Sub SerialPort1_DataReceived(ByVal sender As Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived
    tbxIn.Text = e.ToString
End Sub
End Class

PRetty sure this will get you what you need. You DON't need the Serial1 component on the designer. Remove that and use this code:

    Private comPort As IO.Ports.SerialPort = Nothing
Private sComPort As String = ""

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs)
    GetSerialPortNames()
End Sub

Sub GetSerialPortNames()


    ' Show all available COM ports.    
    For Each sp As String In My.Computer.Ports.SerialPortNames
        lstPorts.Items.Add(sp)
    Next
End Sub

Private Sub lstPorts_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles lstPorts.SelectedIndexChanged
    sComPort = lstPorts.SelectedItem
    Button1.Enabled = True
End Sub

Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click


    ' Open the serial port using the OpenSerialPort method    
    Button1.Enabled = False
    Button2.Enabled = True
    Try


        comPort = My.Computer.Ports.OpenSerialPort(sComPort, 9600, IO.Ports.Parity.None, 8, 1)
        ' comPort.DtrEnable = True      

        'must add handler
        AddHandler comPort.DataReceived, AddressOf SerialPort1_DataReceived

        comPort.ReadTimeout = 500
        Do
            comPort.WriteLine("Go")
            Dim sIncomming As String = comPort.ReadLine()
            tbxIn.Text = sIncomming & vbCrLf
        Loop
    Catch ex As TimeoutException
        tbxIn.Text &= "Error: Serial Port Read Timeout" & vbCrLf
    End Try
End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
    comPort.Close()
    'remove handler
    RemoveHandler comPort.DataReceived, AddressOf SerialPort1_DataReceived
    Button1.Enabled = True
    Button2.Enabled = False
End Sub
Private Sub SerialPort1_DataReceived(ByVal sender As Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs)
    tbxIn.Text = e.ToString
End Sub