BAPI_SHIPMENT_CHANGE Issue

Hi,

I'm trying to change a shipment field using the code below, but so far it didn't get updated. Could you please help me?

            RfcRepository repo = destination.Repository;

            IRfcFunction salesShip = repo.CreateFunction("BAPI_SHIPMENT_CHANGE");

            IRfcFunction salesShipCommit = repo.CreateFunction("BAPI_TRANSACTION_COMMIT");

            IRfcStructure salesShipHeader = salesShip.GetStructure("HEADERDATA");

            salesShipHeader.SetValue("SHIPMENT_NUM", "0011406654");

            salesShipHeader.SetValue("SERVICE_AGENT_ID", "30003367");

            IRfcStructure shipHeaderAction = salesShip.GetStructure("HEADERDATAACTION");

            shipHeaderAction.SetValue("SERVICE_AGENT_ID", "X");

            RfcSessionManager.BeginContext(destination);

            salesShip.Invoke(destination);

            salesShipCommit.Invoke(destination);

            RfcSessionManager.EndContext(destination);

I don't receive any error message in the return.