To addon a domain you need to point the nameservers to our hosting or create a A record on your remote DNS to point to our servers. Propagation could take days in some cases dependant on your registrar or domain type. If this is the case ticket us and we can add the domain on for you. You can check the DNS status at https://www.whatsmydns.net/ enter your domain and select the NS option.
Birch Hosting Ltd