Shipping an ItemFulfillment

I am trying to mark an ItemFulfillment as shipped with a package. The ItemFulfillment record is initially created and picked using WMS Lite RF Mobile Screen.
It is updating the Status field, but it seems to be adding a default package (0.05lb, no description or tracking) instead of the package I specified. What am I doing wrong?
Here is my code (C#):

//curShipment is an EasyPost shipment after purchasing postage.  //it contains relevant information about the package  ItemFulfillmentPackage package = new ItemFulfillmentPackage();  package.packageWeight = curShipment.parcel.weight;  package.packageWeightSpecified = true;  package.packageTrackingNumber = curShipment.tracking_code;  package.packageDescr = "H2OShip Shipment";    ItemFulfillmentPackageList packages = new ItemFulfillmentPackageList();  packages.package = new ItemFulfillmentPackage[] { package };    ItemFulfillment fulfillmentUpdate = new ItemFulfillment();  fulfillmentUpdate.internalId = curFulfillment.internalId;  fulfillmentUpdate.shipStatus = ItemFulfillmentShipStatus._shipped;  fulfillmentUpdate.shipStatusSpecified = true;  fulfillmentUpdate.packageList = packages;    SetNetsuitePrefs(); // Sets preferences and authenticates, similar to the ERP example code  WriteResponse response = await System.Threading.Tasks.Task<SearchResult>.Run(() => { return nsService.update(fulfillmentUpdate); });