killeenshaolinkungfu.com and www.killeenshaolinkungfu.com are technically two different names. You need to get a new certificate that includes both of them.
How did you get this certificate?
As an example, if you ran "certbot --apache -d killeenshaolinkungfu.com", you need to run "certbot --apache -d killeenshaolinkungfu.com -d www.killeenshaolinkungfu.com".