Please check if your name server is responsible for the domain. you can do that by running
Yes it is. This information was seen on the pingability.com test as well.
; <<>> DiG 9.3.2 <<>> ns example.com
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 50379
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;example.com. IN NS
;; ANSWER SECTION:
example.com. 86400 IN NS slv1.1and1.com.
example.com. 86400 IN NS ns1.example.com.
;; Query time: 457 msec
;; SERVER: 188.8.131.52#53(184.108.40.206)
;; WHEN: Wed Jun 11 10:44:21 2008
;; MSG SIZE rcvd: 74
Checked, and it's not blacklisted from the servers that responded. 5 servers timed out.