Problem z zatrzymaniem backgroundworkerka

[Tomeczek3]

Witam.

Tworze mały program, który będzie pokazywał ping i ewentualnie stracone pakiety. 

Imports System.ComponentModel
Imports System.Net
Imports System.Net.NetworkInformation
Imports System.Threading
Public Class Form1
    Dim ping As New Ping
    Dim rp(2) As PingReply
    Private Sub ListBox1_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ListBox1.SelectedIndexChanged

    End Sub

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load


    End Sub

    Private Sub Panel1_Paint(sender As Object, e As PaintEventArgs) Handles Panel1.Paint

    End Sub

    Private Sub Label3_Click(sender As Object, e As EventArgs) Handles Label3.Click

    End Sub

    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
        Form3.Show()
    End Sub

    Private Sub BackgroundWorker1_DoWork(sender As Object, e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
        rp(0) = ping.Send(My.Settings.pingaddres)
    End Sub

    Private Sub BackgroundWorker1_RunWorkerCompleted(sender As Object, e As RunWorkerCompletedEventArgs) Handles BackgroundWorker1.RunWorkerCompleted
        ListBox1.Items.Add("Pinged succesfull: " & rp(0).RoundtripTime & "ms")

    End Sub

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

        BackgroundWorker1.RunWorkerAsync()


    End Sub

    Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
        BackgroundWorker1.CancelAsync()
    End Sub
End Class

No i teraz mam problem. Chciałbym żeby button3 zatrzymywał mi backgroundworkera dlatego wpisałem cancelasync, ale w programie wywala błąd. Jak to zrobić ? Jestem laikiem. 

[Crossiik]

Proponuję użyć zwykłego timera.

    Public Shared Function GetPingMs(ByRef hostNameOrAddress As String)
        Dim ping As New System.Net.NetworkInformation.Ping
        Return ping.Send(hostNameOrAddress).RoundtripTime
    End Function
    Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
        Label1.Text = GetPingMs("188.68.252.139")
    End Sub