If you have added additional domain in DirectAdmin control panel but can't find it in domain list, it's probably DNS zone problem. To get this problem solved, you need admin level access. If you're not owner of the server, please contact us via live chat or ticket system.

If you have admin access, login as admin and go to DNS Administration. In the search field enter domain name that's not showing up in domain list and click Search. If this domain have been founded, it needs to be deleted by selecting the checkbox and clicking Delete. DNS zone record will be removed and you can try to add additional domain again.