Отбор записей из текстового файла в combobx е

Private lst As Dictionary(Of String, String)
Private Sub Load_Click(sender As System.Object, e As System.EventArgs) Handles Button2.Click
    Dim ln() As String = IO.File.ReadAllLines("assortment.txt")
    lst = New Dictionary(Of String, String)
    Dim ss(1) As String
    For Each s As String In ln
        ss = s.Split("|"c)
        If lst.ContainsKey(ss(0)) Then
            lst.Item(ss(0)) &= ", " & ss(1)
        Else
            lst.Add(ss(0), ss(1))
        End If
    Next
    ListBox1.Items.AddRange(lst.Keys.ToArray)
    ListBox1.SelectedIndex = 0
End Sub
Private Sub ListBox1_SelectedIndexChanged(sender As System.Object, e As System.EventArgs) Handles ListBox1.SelectedIndexChanged
    Dim s As String = ""
    lst.TryGetValue(ListBox1.SelectedItem, s)
    TextBox1.Text = s
End Sub

ComboBox2.Items.Add(s)

 If lst.ContainsKey(ss(0)) Then
            lst.Item(ss(0)) &= ", " & ss(1)
        Else
            lst.Add(ss(0), ss(1))
        End If

Private Sub ListBox1_SelectedIndexChanged(sender As System.Object, e As System.EventArgs) Handles ListBox1.SelectedIndexChanged
    Dim s As String = ""
    lst.TryGetValue(ListBox1.SelectedItem, s)
    ListBox2.Items.Clear()
    Dim ss() As String = s.Split(","c)
    ListBox2.Items.AddRange(ss)
    'TextBox1.Text = s
End Sub