You can check the eligibility from Here but make sure that the domain is created on your hosting server. Else, it will display an error.
I am your customer and I’m getting this error!
If your domain .de is not hosted on our US Server, you may see this error. Our UK/Canada server is not suitable for hosting .de domains. If you placed an order on this particular server by mistake, you can open a ticket with us for changing your server location to US.
How to resolve this error? (For other hosting providers who can’t find a solution anywhere.)
1. Make sure that you already created a hosting account on your server with proper DNS nameserver.
2. You can get more info about the error from here (It will show the exact error.)
3. Make sure that both of your nameservers use unique IP addresses and not the same on. Otherwise you will get similar errors like error 901, Invalid RCODE, etc.