Verify that the authorized pickup person is "active" for the relevant enrollment year. Navigate to the profile page for the authorized pickup (go to the camper's family profile and click the "Authorized Pickups" tab, then click the authorized pickup person's name). Click the tab that corresponds with the relevant enrollment year.
If "Active?" says No, the authorized pickup is not actively authorized for that enrollment year, so their PIN will be rejected by the PIN pad. Parents can re-authorize pickups via the Authorized Pickups page of their dashboard, or an admin can do it manually by toggling the Active? setting from No to Yes and clicking OK to save.
If the pickup person is active, ensure that they're using the correct PIN. If needed, an admin can reset the pin via the Action Menu on the authorized pickup's profile.