listbox databinding gets bungled

I have a very simple two-tier listbox: changing value in Top loads a new array to Bottom. The Top is bound to arrTop , a collection of clsTop, which in turn is a collection of clsBot's.

Now, all works fine until i put ANY code at all into the Bottom listbox SelectedValueChanged routine. Then the text in the bottom listbox stops showing. The values are there, i can click on them, but their color is white on white.

Here's the code (the SelectedValueChanged is at the bottom):

VB Code:

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        arrTop = New ArrayList
        Dim newLine As New clsTop
        newLine.Name = "Top1"
        newLine.Add(New clsBot("1-1"))
 
 
 
        Dim newLine2 As New clsTop
        newLine2.Name = "top2"
        newLine2.Add(New clsBot("2-1"))
        newLine2.Add(New clsBot("2-2"))
        newLine2.Add(New clsBot("2-3"))
        newLine2.Add(New clsBot("2-4"))
        newLine2.Add(New clsBot("2-5"))
        newLine2.Add(New clsBot("2-6"))
        newLine2.Add(New clsBot("2-7"))
        newLine2.Add(New clsBot("2-8"))
        newLine2.Add(New clsBot("2-9"))
        newLine2.Add(New clsBot("2-10"))
 
 
        arrTop.Add(newLine)
        arrTop.Add(newLine2)
        lstTop.DataSource = Nothing
        lstTop.DataSource = arrTop
        lstTop.DisplayMember = "Name"
 
    End Sub
 
    Private Sub lstTop_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles lstTop.SelectedIndexChanged
        lstBot.DataSource = Nothing
        lstBot.DataSource = lstTop.SelectedValue
        lstBot.DisplayMember = "Name"
    End Sub
 
 
    Private Sub lstBot_SelectedValueChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles lstBot.SelectedValueChanged
        Dim curBot As clsBot = lstBot.SelectedValue
        chkProcessed.Checked = curBot.Processed
        If Not curBot.Processed Then curBot.Process()
        lstBot.Refresh()
        'lstBot.ForeColor = Color.AliceBlue
    End Sub