AfterShip automatically detect the courier of each shipment based on its tracking number format. While AfterShip supports over 70 couriers, the same tracking number format may clash with multiple couriers. In this case, you will want to tell AfterShip which courier you're actually using, i.e. set a courier priority for your AfterShip account.
You can now select your preferred couriers for tracking at your AfterShip account ()Settings). Activate couriers you wish to use, and drag the courier you use to the top if you want to give it a higher priority. So that for the case of tracking number format matches two or multiple carriers, AfterShip knows which courier it should choose for your account. See below the screen shot. If you still have any questions, email me at firstname.lastname@example.org