You just need to add the DNS server "A" entries in the zone file on the new server so that they can pull the resolution for the new DNS server IPs.
It's a common check a lot of registars are using these days ...
You could do this from WHM in "Edit a DNS Zone" or from the SSH shell:
Code:
# cd /var/named
# pico domainname.fr.db
# service named restart
While editing the zone file in pico (or VI *my personal choice*),
you need to add "A" records for your DNS servers.
Code:
ns1 (or whatever you call your DNS server) IN A x.x.x.x
ns2 IN A y.y.y.y