AIF Sales Order Create - SalesType being set to Journal

When I create a new sales order through the AIF through a C# client, the SalesType gets set as Journal, even though I am specifying it to be a ReturnItem, see below:

            var salesOrder = new AxdEntity_SalesTable

            {

                CustAccount = "CUS1363",

                SalesType = AxdEnum_SalesType.ReturnItem,

                SalesTypeSpecified = true,

                SalesOriginId = "PZO",

                SalesPoolId = "VOR",

                DlvMode = "TNT-ND"

            };