Help! Try to use Serial Port in Pocket PC in VB.NET!

[Bianca Zhang]

Hi, all!
Im trying to bulid the connection between Pocket PC and a certain Bluetooth device. I've tried to use the Outbound COM port, in my case is COM8, to let the Pocket PC as a server. i've received the build in pair request from the bluetooth device. And seems the data does transmitted. but I encountered the problem that, after i choose the desired device, got error shows COM8 does not exist.
the code i wrote is like,

Imports System.IO
Public Class Form1
    Dim ReadData
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        If SerialPort1.IsOpen Then
            SerialPort1.Close()
        End If

        SerialPort1.PortName = "COM8" 'Outbound Com port in Pocket PC
        SerialPort1.BaudRate = 38400 'Needed for the bluetooth device
        SerialPort1.Parity = IO.Ports.Parity.None
        SerialPort1.DataBits = 8
        SerialPort1.StopBits = IO.Ports.StopBits.One
        SerialPort1.RtsEnable = True

        SerialPort1.RtsEnable = True
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        If SerialPort1.IsOpen Then
        Else
            SerialPort1.Open()
        End If

        ReadData = SerialPort1.ReadExisting
        TextBox1.Text = ReadData
    End Sub
End Class

i heard that the 1st thing need to make sure is the bluetooth device have smth like 'out going serial port'. is that the problem?
Can anyone help me with this?
Thanks in advance!