hotlink protection not working for subdomains

I'm trying to prevent hot linking on my server. So far I've been able to prevent hot linking to [mysite.com...] but NOT [subdomain.mysite.com...]

Am I to understand that each subdomain folder needs its own copy of the modified htaccess to prevent this?

jdMorgan in this thread (http://www.webmasterworld.com/forum92/1449.htm) says this is the case but I'd like some confirmation.

I've tried several variations of hot link protection htaccess code but NONE of it has prevented hot linking to my sub domains.

This is kind of a big deal for me because _all_ of my site(s) are based around sub domains so it'll be a real PITA if this is the case.

Thanks

works for mysite.com but not sub.mysite.com