validate a certificate


Hello, for the first time I am trying to publish an app in the apple stores. Unfortunately I stopped when I try to open the Apple notification push certificate (aps.cer) in keychain access. apparently the certificate is not seen in the keychain because it is not validated. Can you give me some directions?
Thank you for your availability
Confirm your process here:

https://developer.apple.com/documentation/usernotifications/setting_up_a_remote_notification_server/establishing_a_certificate-based_connection_to_apns

Come back with any specific issues, being sure to show any errors, etc., don't paraphrase.

validate a certificate
 
 
Q