Problem with subdomain delegation - NS RR ignored?

[binduser at thegeezer.net]

Howdy

I'm struggling with subdomain creation, for some reason the delegation 
glue records are being ignored - and i was wondering if someone could 
help me identify what I've done wrong please.  I know i need to setup 
another server for the subdomain, but I've been trying to get this going 
at work and getting the same issue, so thought to try on my test bed.  
Can't even get the NS record returned for the subdomain

Given the domain ".hub"  I can verify the domain level NS
# host -t NS hub localhost
 > hub name server localhost.

I can create an A record  for "salmon.hub."  and this resolves as expected:
# host -t a salmon.hub localhost
 > salmon.hub has address 8.8.8.8

I want to delegate to a different domain server the subdomain "fish.hub" 
and have created glue records as below in the config snippet, but get 
NXDOMAIN for both the A record and the NS record
# host -t a ns1.fish.hub localhost
 > Host ns1.fish.hub not found: 3(NXDOMAIN)

# host -t NS fish.hub localhost
 > Host fish.hub not found: 3(NXDOMAIN)

Any suggestions gratefully received.  Pertinent parts of named.conf and 
zone file are shown below, if you need more info please don't hesitate 
to ask

thanks in advance!

TG

/etc/bind/named.conf
acl "trusted" {
         10.0.0.0/8;
         192.168.0.0/16;
         127.0.0.0/8;
         ::1/128;
};
allow-recursion {
                 trusted;
        };
forwarders {
                 208.67.220.220;
                 208.67.222.222;
         };
zone "hub" IN {
                type master;
                file "pri/hub.zone";
                notify no;
         };

/etc/bind/pri/hub.zone
$TTL 1W
@       IN      SOA     hub. root.hub.  (
                                       2008122601 ; Serial
                                       28800      ; Refresh
                                       14400      ; Retry
                                       604800     ; Expire - 1 week
                                       86400 )    ; Minimum
@               IN      NS      localhost.
@               IN      A       127.0.0.1

@               IN      AAAA    ::1

salmon.hub.     IN      A       8.8.8.8
fish.hub.       IN      NS      ns1.fish.hub.
ns1.fish.hub.   IN      A       4.4.4.4