DNS zone forwarding doesn't work in RHEL5

Issue

• A zone forwarding was configured in /etc/named.conf:

zone "myserver.com" {
     type forward;
     forwarders { x.x.x.x ; };
     forward only;
};

• When nslookup command is used it works.
• But when dig command is used, it fails with a time out:

# dig www.myserver.com
; <<>> DiG 9.3.6-P1-RedHat-9.3.6-20.P1.el5_8.5 <<>> www.myserver.com
;; global options:  printcmd
;; connection timed out; no servers could be reached