My skill keeps failing certification because Amazon claims that our certificate is not signed by a trusted authority. The endpoint is https://www.rei.com/alexa/assistant. We have a wildcard certificate provided by Akamai and issued by Symantec Class 3 Secure Server CA - G4. I have chosen the certificate option, "My development endpoint is a sub-domain of a domain that has a wildcard certificate from a certificate authority". www.rei.com should be a valid subdomain of the wildcard. If you verify the chain at https://www.ssllabs.com/ssltest/analyze.html?d=www.rei.com you will see that it has an "A" rating.