"Invalid distance education authorization code" means that the authorization code (also called activation code or registration code) cannot effectively activate or register the "distance education" service. Generally speaking, authorization codes are used to verify the identity of users and gain access to software or services. The authorization code has expired or been revoked, which makes it impossible to activate or register the service. This is because the validity period of the authorization code has expired, or the generation or distribution of the authorization code is incorrect. "Invalid distance education authorization code" means that the authorization code (also called activation code or registration code) cannot effectively activate or register the "distance education" service.