At some point you created NS contacts for ns1.nameserver.com and ns2.nameserver.com with your registrar (ENOM, Joker, Dotster, etc).
Your registrar then informed the root servers for the .net/.com/.org tLD's of the NS contact and it was added to the root servers managed by VeriSign (gtld-servers.net).
ICANN later gave management of the .org tLD to PIR (Public Internet Registry) (
http://www.pir.org/).
New NS registrations with VeriSign or an SRS registrar will not work with .org domains by default now. The existing NS contacts for .org before the change of administration from VeriSign to PIR where transferred automatically and you can use those name servers for .org domains.
ICANN also approved the creation of additional tLD's (.biz, etc) managed by various originations (
http://www.icann.org/tlds/ for more information).
The .us tLD is now being managed by NeuStar (
www.nic.us).
The point of all this is the other tLD's do not have a NS contact if your initial registrar did not register them with the additional tLD registries. You will not be able to use those name servers until there added to the appropriate registries.
If you would like the NS contacts added to the registries. Please email the hostnames and addresses of the name servers to
greg@rackshack.net
We are working on automating the addition of NS contacts with the .us, .biz, etc. tLD registries automatically when you attempt to add a NS that is only registered with the .com/.net tLD's.