Why do I get the error "Missing or Invalid Shipper Number" from UPS?

Your UPS Shipper Number must be linked to your UPS.com account (username and password) that you have entered into ShipHero.

To resolve this error:
  1. Log in to ups.com using your UPS username and password
  2. Hover over your name in the top right corner of the screen, and select "Payment Options" from the dropdown.
  3. Verify your shipper number is listed; if not, select the Add a Payment Method dropdown, and add your UPS Shipper number.
  4. After completing steps 1 through 3, please add the UPS Username, Password, and Shipper Number to ShipHero from Shipping>Carriers