Private Sub CommandButton2_Click()
Dim TB As Worksheet
Dim Rng As Range
Dim i%
Dim Adr$
    With ComboBox1
        Adr = Right(.RowSource, Len(.RowSource) - InStr(.RowSource, "!"))
        Set TB = Worksheets(Left(.RowSource, InStr(.RowSource, "!") - 1))
        Set Rng = TB.Range(Adr)
        On Error Resume Next
        IsError (WorksheetFunction.Match(.Text, Tabelle1.Range(Adr), 0))
        If Err > 0 Then
            Set Rng = Rng.Resize(Rng.Rows.Count + 1, Rng.Columns.Count)
            Rng.Cells(Rng.Cells.Count) = .Text
            .RowSource = TB.Name & "!" & Rng.Address
        End If
    End With
End Sub

