Dynamics GP Web Service not setting Front Office Integration ID

Question

I am working with the Dynamics Great Plains web service and running into an issue with the Front Office Integration ID being set.

SalesOrderLine so_line = new SalesOrderLine();

            so_line.PriceLevelKey = new PriceLevelKey() { CompanyKey = proxy.CompanyKey, Id = "4" };
            so_line.UnitPrice = new MoneyAmount() { Value = 12.49M };
            so_line.Quantity = new Quantity() { Value = 1 };
            so_line.Discount = new MoneyPercentChoice() { Item = new MoneyAmount() { Value = 1.25M } };
            so_line.FrontOfficeIntegrationId = "802L0000000X1RNIA0";

            so_line.ItemKey = new ItemKey() { CompanyKey = proxy.CompanyKey, Id = "HAAL" };
            so_line.UofM = "EACH";
            so_line.RequestedShipDate = DateTime.Parse("2/26/2018");

Any thoughts on why this 802 string would not be saved to the line on createSalesOrder method?