Bill Creation using SOAP fails

Here is the code:

            string lcSQL, lcErrMsg, lcStage = "Start";

clsGlobals.gcAcmtURL="http://localhost/AcumaticaERP/";
clsGlobals.gcAcmtEndPoint="Default";
clsGlobals.gcAcmtVersion="17.200.001";

            AcmtIntegrator.AcumaticaWSDL.DefaultSoapClient soapClient = null;
            soapClient = new AcmtIntegrator.AcumaticaWSDL.DefaultSoapClient(clsACMT.CreateBinding(clsGlobals.gcAcmtURL),
            clsACMT.CreateEndpoint(clsGlobals.gcAcmtURL, clsGlobals.gcAcmtEndPoint, clsGlobals.gcAcmtVersion));

            string lcBranch, lcLocationID;
 

            // Bill Level:
            lcBranch = "SOFT";
            lcLocationID = "";
            string docType = "Bill";
            string lcVendorCd = "EP00000001";
            string lcVendorRef = "VendorRef - 2";
            decimal lnBillAmt = 1000;
            string lcDocTxnDate = "20201005", lcDocDueDate = "20201104";
            string lcCashAccount = "102000SOFT";
            string lcBillDesc = "bill Desc 2";
            string lcRefNo = "RefNo";
            string lcTerms = "30D";
            string lcPostPeriod = "102020";

            int lnLineCount = 0;
            lnLineCount = 1;

            // Bill Line
            decimal lnLineExtAmt = 1000, lnUnitCost = 0, lnLineQty = 0;
            string lcLinePOOrderNbr = "", lcLinePOOrderType = "", lcLineDesc = "Line Desc", lcLineTranDesc = "Tran Desc";
            string lcLineAccount, lcLineSubAccount, lcUoM, lcLineItemInvID, lcLineProject = "Prj", lcLineProjectTask = "PTask";
            string lcItemAcmtGuid = "61594ca1-0d6b-e411-a445-e06995c86014";

            //

            BillDetail[] loBillDetails;
            loBillDetails = new BillDetail[lnLineCount];

            lcLineItemInvID = "ADVERT";
            lcLineDesc = "Advertising";
            lcLineAccount = "610000";
            lcLineSubAccount = "0000000";
            lcUoM = "HOUR";

            loBillDetails[0] = new BillDetail
            {
                Branch = new StringValue { Value = lcBranch },
                Amount = new DecimalValue { Value = lnLineExtAmt },
                ExtendedCost = new DecimalValue { Value = lnLineExtAmt },
                UnitCost = new DecimalValue { Value = lnUnitCost },
                Qty = new DecimalValue { Value = lnLineQty },
                TransactionDescription = new StringValue { Value = lcLineTranDesc },
                Description = new StringValue { Value = lcLineDesc },
                POOrderNbr = new StringValue { Value = lcLinePOOrderNbr },
                POOrderType = new StringValue { Value = lcLinePOOrderType },
                Account = new StringValue { Value = lcLineAccount },
                Subaccount = new StringValue { Value = lcLineSubAccount },
                // InventoryID = new StringValue { Value = lcLineItemInvID },
                UOM = new StringValue { Value = lcUoM },
                Project = new StringValue { Value = lcLineProject },
                ProjectTask = new StringValue { Value = lcLineProjectTask }
        };

            Bill loBill = new Bill
            {
                ReturnBehavior = ReturnBehavior.OnlySpecified,
                // ReturnBehavior = ReturnBehavior.All,
                Amount = new DecimalValue { Value = lnBillAmt },
                Applications = new AcmtIntegrator.AcumaticaWSDL.BillApplicationDetail[0],
                ApprovedForPayment = new BooleanValue { Value = true },
                Balance = new DecimalValue { Value = lnBillAmt },
                BranchID = new StringValue { Value = lcBranch },
                CashAccount = new StringValue { Value = lcCashAccount },    
                CurrencyID = new StringValue { Value = "USD" },
                CustomFields = new AcmtIntegrator.AcumaticaWSDL.CustomField[0],
                Description = new StringValue { Value = lcBillDesc },
                Hold = new BooleanValue { Value = false },
                Note = "",  
                Type = new StringValue { Value = docType },
                ReferenceNbr = new StringReturn { Value = lcRefNo },
                // ReferenceNbr = new StringReturn(),
                TaxDetails = new AcmtIntegrator.AcumaticaWSDL.BillTaxDetail[0],
                // Type = new StringValue (),  
                // Status = new StringReturn(),
                Status = new StringReturn { Value = "Balanced" },
                Vendor = new StringValue { Value = lcVendorCd },
                VendorRef = new StringValue { Value = lcVendorRef },
                PostPeriod = new StringValue { Value = lcPostPeriod },
                TaxTotal = new DecimalValue { Value = 0 },  
                Terms = new StringValue { Value = lcTerms },
                Details = loBillDetails,
            };

            // LocationID is optional
            if (lcLocationID != "")
            {
                loBill.LocationID = new StringValue { Value = lcLocationID };
            }

            if (lcDocTxnDate != "")
            {
                loBill.Date = new DateTimeValue
                {
                    Value = new DateTime(Convert.ToInt32(mdlGU.MyLeft(lcDocTxnDate, 4)),
                    Convert.ToInt32(lcDocTxnDate.Substring(4, 2)),
                    Convert.ToInt32(lcDocTxnDate.Substring(6, 2)))
                };

                loBill.DueDate = new DateTimeValue
                {
                    Value = new DateTime(Convert.ToInt32(mdlGU.MyLeft(lcDocDueDate, 4)),
                    Convert.ToInt32(lcDocDueDate.Substring(4, 2)),
                    Convert.ToInt32(lcDocDueDate.Substring(6, 2)))
                };

            };

            //Create a Bill
            Bill newBill = new Bill();
            try
            {
                newBill = (Bill)soapClient.Put(loBill);
            }
            catch (Exception ex)
            {
                lcErrMsg = ex.Message.Replace("'", "").Substring(0, 900);
            }

            soapClient.Logout();

Thank you!

I checked that a copy of an existing Bill can be saved by Put, so there is no issue with permissions to save.

The only Nulls that I could find in loBill were ID and RowNumber.