CPanel Migration - Sub Domains Not Working

I’m new to Virtualmin and I’ve tried to migrate a bunch of sites using CPanel backups. Most of the primary domains have transferred over without a hitch - but none of my subdomains are working.
I understand that Virtualmin uses sub servers so I tried converting one of the problem sub domains to a sub server (was this the right thing to do?) - but that didn’t work.

I’m just getting server 500 errors if I try to access any of the sub domains in a browser.
Any suggestions or pointers toward something useful would be greatly appreciated.
Thanks.

BTW:
Operating system CentOS Linux 6.5

Howdy,

Hmm, when you receive those 500 errors, what message appears in the Apache logs for that sub domain?

The Apache logs are typically in $HOME/logs/error_log (or in the case of a Sub-Server, $HOME/domain/DOMAINNAME/logs/error_log).

-Eric