depends on where you installed your SSL
if you installed it on https://www.domain.com then it'll only work on that
and if you installed it on https://domain.com then it'll only work on that one.
If you installed a wildcard certificate it should work on both and subdomains as well, but wildcard certificates cost 10 times more then normal SSL
when you go into WHM and look at the domains IP address do you see the 443 after the IP ?
like 69.111.69.111:443 ?
If thats the case you have installed SSL and if you can NOT see the 443 after the IP you havent installed SSL on that dedicated IP