Dim orders As IEnumerable(Of DataRow) = osql.dt.AsEnumerable Dim Test2 = From r In orders _ Group r By nummer = r.Field(Of String)("KL_Nummer"), name = r.Field(Of String)("KL_Naam"), artBtw = r.Field(Of Double)("ArtBtw") _ Into g = Group Select New With {.Nummer = nummer, .Name = name, .artbtw = artBtw, .total = g.Sum(Function(r) _ r.Field(Of Decimal)("Bestd_Waarde") * (1.0 - CDbl(If(r("art_korting") = False, 0.0, If(r("kkkorting") Is DBNull.Value, CDbl(r("KLkorting")), CDbl(r("KKKorting")))))))} Dim test = From r In Test2 Order By r.Name