我的进度条正在消失

Question

一旦我开始运行任何代码，我的进度条就会消失。为什么？ 那真的很奇怪。

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

    StartThinking()

    For Each z In ListBox1.Items
        Dim u = FindIPAddress(z)
        ListBox2.Items.Add(If(IsNothing(u), "Not found!", u))
    Next

    StopThinking()

End Sub

Sub StartThinking()
    Cursor = Cursors.WaitCursor
    ProgressBar1.Minimum = 0
    ProgressBar1.Style = ProgressBarStyle.Marquee
End Sub

Sub StopThinking()
    ProgressBar1.Minimum = ProgressBar1.Maximum
    ProgressBar1.Style = ProgressBarStyle.Blocks
    Cursor = Cursors.Arrow
End Sub