redirect my subdomain to forum

Hi,
I've followed all the steps from the FAQ but still couldn't redirect my subdomain to my forum address. It is said that I need a CNAME redirecting to my forum, which I did already. what did I miss here?? Please help me. Thanx a lot.

Your subdomain will always be your forum; that's the URL hat u get when you create your forum.

The redirecting & CNAME Alias refers to when you purchase a domain name.

You can't redirect a subdomain anywhere -> Ever (On a forumotion forum)

No, what I meant I have a subdomain from my own domain address (forum.mydomain.com) that I want to redirect to myforum.forumotion.net So that everytime I type forum.mydomain.com it will takes me to myforum.forumotion.net and forum.mydomain.com will be my forum's address.

Your sub domain (name.subdomain.com) automatically redirects to your personalised domain (name.domain.com), just you can tick the box "Force redirection" means that the user, if typed in the subdomain will see the domain, where as if you leave the box un-ticked, the user who types in the domain, will see the domain, and a user whom types in the sub-domain, will see the sub domain.

It seems that you've brought ur domain externally, so this tutorial should help out
=> https://help.forumotion.com/frequently-asked-questions-f5/redirect-an-extern-domain-name-that-you-own-to-your-board-t7021.htm