Can FTH Use Subdomain Of Custom Domain?

This is for club 1293995

We *were* using a custom domain, now we'd like to break out our "www" to a different website, and do something like:

members.customdomain.com

FTH chokes and generates an error when I try to put that in the "custom domain" field. Is that not supported?

If not we'll just do the toastmastersclubs.org thing with our club name as a subdomain - no big deal. But I just wanted to clarify whether this *should* be possible, and I'm just doing something wrong.

The subdomain is configured at the registrar, so everything should be good on that front.

Any advice?

sorry no.