'Laenge
   If Decimal.TryParse(txtlaenge.Text, laenge) Then
      Dim filterlaenge As Decimal = _
           Aggregate row As DataRow In dt.AsEnumerable _
              Where Not IsDBNull(row("Laenge")) AndAlso _
                    laenge <= CDec(row.Field(Of String)("Laenge"))
           Into Min(CDec(row.Field(Of String)("Laenge")))
 
      filter = "Convert(Laenge, 'System.Decimal') = " & _
      filterlaenge.ToString(System.Globalization.CultureInfo.InvariantCulture)
   End If