dig: Transfer failed

[Stayvoid]

Hi,

dig <three-octets>.in-addr.arpa. AXFR outputs "Transfer failed."

I've already checked "netstat -anp." Looks OK.
dig <my-domain> works.
sudo named-checkzone <my-domain> /etc/bind/db.<my-domain> outputs "OK."
sudo named-checkzone <three-octets>.in-addr.arpa. /etc/bind/db.<first-octet>
outputs "OK" too.

What should I check?

Cheers