Domain mapping

Hi, I have a question.

I have a pre registered domain on Enom.

Iam trying to map that on a sub site on sub domain.

I have logged in to Enom and chnaged A record to the IP of the sever.

Yet i still get an error while trying to map it.

We can’t access your new domain. Mapping a new domains can take as little as 15 minutes to resolve but in some cases can take up to 72 hours, so please wait if you just bought it. If it is an existing domain and has already been fully propagated, check your DNS records are configured correctly

What step am i missing ?
Thanks