is mysql installed and running and is the domain configured to use it, as in server templates-Default domain owner limits.
Check mysql database so the domain can use it.
Maybe. You haven’t told us the OS and version, so I can’t be terribly specific.
In short, you need to make sure the Webmin MySQL module knows where MySQL lives and is able to connect to it as the root user–you may need to provide the password to Webmin. So, browse to the Webmin:Servers:MySQL Database Server module, and see if things are working there. Virtualmin only knows about services that Webmin knows about.