在select使用自定义的静态函数，出现"no support Check if the "...错误 返回

在下面的Select中使用自定义静态函数ConvertServiceIDToSTS

出现"ConvertServiceIDToSTS(it1.ServiceID)no support Check if the navigation is configured correctly or Includes() is missing"的错误，

请教该如何解决？

            int ret = db.Queryable<InvoiceDetailModel>()
                        .IncludeLeftJoin(it1 => it1.Customer)
                        .LeftJoin<InvoiceNoticeModel>((it1, it2) => it1.InvoiceCD == it2.InvoiceCD && it1.InvoiceDate == it2.InvoiceDate)
                        .Where((it1, it2) => it1.InvoiceDate == invoiceDate && servList.Contains(it1.ServiceID))
                        .WhereIF(!isBulk, (it1, it2) => customerList!.Contains(it1.CustomerID))
                        .Select((it1, it2) => new InvoiceDetailIFModel
                        {
                            ID = it1.ID,
                            CustomerID = it1.CustomerID,
                            InvoiceCD = it1.InvoiceCD,
                            CustomerName = it1.Customer!.CustomerName,
                            SlipDate = DateTime.Parse($"{it1.SalesDate}/01"),
                            InvoiceYM = it1.InvoiceDate,
                            //ServiceID = it1.ServiceID,
                            ServiceID = Constants.ConvertServiceIDToSTS(it1.ServiceID),
                            SectionCD = it1.SectionCD,
                            BulkNo = it1.BulkNo,
                            Notice = it2.Notice,
                            Notice2 = it2.Notice2,
                            ApprovalNo = it1.ApprovalNo,
                            PreID = it1.PreID,
                            ItemCD = it1.ItemCD,
                            ItemName = it1.ItemName,
                            Qty = it1.Qty,
                            UnitCost = it1.UnitCost,
                            TaxCode = "2",
                            TaxRate = taxRate,
                            Note = it1.Note,
                            ElementCD = it1.ElementCD,
                            Sort = it1.Sort,
                            UpdateTime = it1.UpdateTime,
                            IsDeleted = it1.IsDeleted
                        })
                        .IntoTable<InvoiceDetailIFModel>();