Problem With Domain Forwarding

Hi. I am having problem redirecting my domain to my forum.

My domain: http://www.rapidarmy.com
My forum address: http://rapidarmy.forumotion.net

At the moment, the problems i faced are:-

1) It redirects to https://www.forumotion.com/en/search/www.rapidarmy.com instead of my forum address.
2) when i set my personalised domain name in the "General > Forum > FORUM Address, i get this error.

Error

The supplied domain name is not well configured
You have no CNAME redirecting to : rapidarmy.forumotion.net
You have configured a A type DNS ( A type redirects to an IP address, and not to a textual domain name like the CNAME )

I have tried configuring the cname, and i am still having this problem. Can someone tell me what is wrong with my setting?

I already tried the tutorial in https://help.forumotion.com/frequently-asked-questions-f5/redirect-an-extern-domain-name-that-you-own-to-your-board-t7021.htm and the same problem exist.

Please do help me