WPF Listbox Scroll to Bottom VB.Net

I am developing a WPF application that has a listbox.  In a standard windows form when I added an item to a listbox I could just use the TopIndex feature but that is not available in a WPF window.  

I have tried ScrollIntoView but I cannot get it to work.  Any help would be appreciated.

Thanks!

Public Sub UpdateStatus(ByVal s As String)
        Dim currDateTime As DateTime = DateTime.Now
        Dim sDateTime As String

        If (s <> gsLine) Then
            sDateTime = currDateTime.ToString("yyyyMMdd-HH:mm:ss> ")
        Else
            sDateTime = ""
        End If
        listStatus.BeginInit()
        listStatus.Items.Add(sDateTime + s)
        listStatus.ScrollIntoView(listStatus.Items.Count - 1)
        listStatus.EndInit()
    End Sub

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