out -of-zone records

[Sam M]

I'm trying to change the name servers of a newly registered domain to my own
for a .be domain via Enom. Unfortunatly something is going wrong and I'm not
sure what it is. Enom is telling me that my name servers ns1.servwise.com
(ns2, ns3 and ns4 etc)  are not in the out-of-zone records for the .be
domain. I've never heard of this although admittedly this is the first .be
domain I've tried to host however I have plenty of other international
domains .it, .eu, .uk using my DNS servers.
 
Can anyone shed some light on to what I need to do to get my domain into the
out-of-zone records for .be?
Regards 
Sam M