Dim dt As DataTable = Me.Dataset1.tblTabelle
   Dim objJahr As Object
   objJahr = dt.Compute("SUM(Kilometer)", "spalteDatum = '" + DatePart("m", _
     "11") + "'")
  If Not objJahr Is System.DBNull.Value Then
            Dim sumMonat As String = CType(objJahr, String)
           lblMonat.Text = sumMonat + " km"
        Else
           lblMonat.Text = "0" + " km" 'string für das aktuelle Jahr
        End If