I have problem in adding new domain

[KangJL]

Since you did not provide any info, we cannot help you.
Best guess is this

Unable to set nameservers: DNS query refused

Before you can add a domain name to your account, you need to point it to the InfinityFree nameservers first. However, some domain providers show an error like this when trying to change the nameservers: DNS Query Refused If that happens, your registrar will tell you that the nameservers must be configured first. What causes this issue Before you can add your domain to your InfinityFree account, you need to verify you can control the domain. The usual way to do so right now is by setting th…