Newly Installed wildcard SSL Cert only works for root domain

[goodbot]

My server had one active webpage: "sub.domain.com". I previously had DA install a dedicated LetsEncrypt certificate (specifically for "sub.domain.net", not a wildcard cert) that worked fine for two months. After it expired, I decided to instead obtain a new LetsEncrypt wildcard certificate at my DNS provider. I obtained this and installed it (at "domain.com"), and for "domain.com", it's working correctly. However, I'm missing some step to now get the old "sub.domain.com" to fall in line and also use this same wildcard certificate... so far "sub.domain.com" is still referencing the old expired certificate. I found the old expired certificate files (at /usr/local/directadmin/data/.lego/certificates/ ) and mv'd them to new names. Afterwards I restarted httpd: Nada... "sub.domain.com" is still referencing the expired certificate (and all browsers are complaining about it). I've also flushed the browser caches repeatedly... NG. Any ideas?