Sometimes Shopify won't automatically add ShipScout to all your Shopify shipping zones. Follow these steps to fix this issue.
1. Click the "edit zone" link in ShipScout
2. Click "Add Rate" for the zone you are trying to fix:
3. Fill out the new Rate popup:
4. Click "save" in the top bar:
5. Back in ShipScout click "refresh zones" and the error should disappear: