'dt.Rows(1)("ShippedDate") = DBNull.Value

    Function RefillDS(ByVal intVariant As Integer)
        Try
            SqlConnection1.Open()
            DsKunden1.Clear()
            SqlDataAdapter1.Fill(DsKunden1.Akquisiteur)
            SqlDataAdapter2.Fill(DsKunden1.Anrede)
            SqlDataAdapter4.Fill(DsKunden1.Branche)
            SqlDataAdapter5.Fill(DsKunden1.Kontakt)
            SqlDataAdapter6.Fill(DsKunden1.Kunden)
            SqlDataAdapter7.Fill(DsKunden1.Prioritaet)
            SqlDataAdapter3.Fill(DsKunden1.Ansprechpartner)
            SqlDataAdapter8.Fill(DsKunden1.Insolvent)
            SqlConnection1.Close()
            'SQL Connection(geschlossen)
        Catch
            MsgBox("Konnte SQL-Verbindung nicht herstellen" & vbCrLf & "Fehler:" & _
              "" & Err.Description)
        End Try
 
        If intVariant = 0 Then
            'Berechnungen für den ListBox Container
            dtTemp = DsKunden1.Kontakt
            dvTemp = dtTemp.DefaultView
            cmTemp = Me.BindingContext(dvTemp)
            'dt.Rows(1)("ShippedDate") = DBNull.Value
            txtNotiz.DataBindings.Add(New Binding("Text", dvTemp, "Bemerkung"))
            bTemp = New Binding("Text", dvTemp, "Datum")
            txtDatum.DataBindings.Add(bTemp)
            AddHandler Me.txtDatum.DataBindings(0).Format, AddressOf _
              Me.FormatDate
        End If
 
        'CurrManager werden an DataViews gebunden
        mobjCurrencyManager = CType(Me.BindingContext(dvKunden), _
          CurrencyManager)
        mobjCurrencyManager2 = CType(Me.BindingContext(dvAnsprechpartner), _
        CurrencyManager)
        mobjCurrencyManager3 = CType(Me.BindingContext(dvKontakte), _
        CurrencyManager)
        mobjCurrencyManager4 = CType(Me.BindingContext(dvAkquisiteure), _
        CurrencyManager)
        mobjCurrencyManager5 = CType(Me.BindingContext(dvBranchen), _
        CurrencyManager)
 
        EndEditCM()
        Me.SqlDataAdapter1.Update(DsKunden1, "Akquisiteur")
        Me.SqlDataAdapter4.Update(DsKunden1, "Branche")
        Me.SqlDataAdapter3.Update(DsKunden1, "Ansprechpartner")
        Me.SqlDataAdapter6.Update(DsKunden1, "Kunden")
        Me.SqlDataAdapter5.Update(DsKunden1, "Kontakt")
        NaviButtonControl()
        NaviFeld()
        buildListBox1()
    End Function

    Private Sub buildListBox1()
        Dim al As New ArrayList()
        Dim drvTemp As DataRowView
        For Each drvTemp In dvTemp
            If drvTemp("Datum") Is DBNull.Value Then
                al.Add(DateTime.MinValue.ToString("dd.MM.yyyy hh:mm"))
            Else
                al.Add(CDate(drvTemp("Datum")).ToString("dd.MM.yyyy hh:mm"))
            End If
        Next
        lbKontakte.DataSource = al
        lbKontakte.SelectedIndex = cmTemp.Position
    End Sub

lbKontakte.SelectedIndex = cmTemp.Position

If it was hard to code, it should be hard to read too.