Can't add new site

I got register a new domain, and after 2 hours, I try to add a new site in Cloudflare, but can’t with reason my domain is not a registered domain. How I can add new site?
Untitled

Whois does show these nameservers, however the registry’s root nameservers do not return those. As long as that doesnt work you wont be able to add your domain. You should contact the registrar and clarify why the domain does not resolve.

Why is now I can’t add more domain .tk or .ga, before I got add many sites like this, it works well. But it now can’t