Nameserver invalid warning from an intoDNS.com test

I made my own nameserver configuration, but as you can see in the picture and the intodns.com link, I am getting a (hostname) warning.

WARNING: At least one of your NS name does not seem a valid host name
The ones that do not seem valid:
ns2.bo(*).works ns1.bo(*).works

Hosting provider nameserver IPs:

5.250.241.34
5.250.242.34

My dedicated IP:

5.250.252.52

My DNS Records:

Domain Provider DNS Settings:

Where am I making a mistake? Do I enter the dedicated IP in the fields? I could not understand! Why am I getting this error? How should it be properly configured?

Most likely there's nothing wrong with the setup, but the tool you are using is reporting...

1. a false positive. Maybe the single test isn't aware of .works being a valid TLD.
2. about something that isn't really a problem. For example there aren't matching reverse DNS PTR records, but that isn't a requirement.