The country associated with Shipper's ShipperNumber must be the same as the shipments Shipper's country.
This error message is from UPS.
Your UPS account number is relevant to one pre-configured country at UPS systems and if you try to create a shipment from different country than the one configured in your account number, you will receive this error from UPS.
You must always use the right pre-configured country as a shipper country code when creating UPS shipments with Packrooster Shipping.