serial port threading

Imports System
Imports System.Threading
Imports System.IO.Ports
Imports System.ComponentModel

Public Class Form1
    Delegate Sub SetTextCallback(ByVal [text] As Char)

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

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        SerialPort1.PortName = "COM50"
        SerialPort1.BaudRate = "2600"
        SerialPort1.Open()
    End Sub

    Private Sub SerialPort1_DataReceived(ByVal sender As System.Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived
        ReceivedText(SerialPort1.ReadExisting())
    End Sub

    Private Sub ReceivedText(ByVal [text] As Char)
        If Me.InvokeRequired Then
            Dim x As New SetTextCallback(AddressOf ReceivedText)

            Me.Invoke(x, New Object() {(Text)})
        Else

            If Text = "A" Then
                Label1.Text = Label1.Text + 1
                Label1.Refresh()
            End If
        End If
    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        Label1.Text = "0000"
    End Sub
End Class