subdomain problem

[hoyoung at us.ibm.com]

Could anyone tell me what I'm missing here?

Parent domain test.com is on server name.test.com. Server ip is 11.13.x.x
Sub domain  sub.test.com is on server namesub.test.com.  Server ip is 11.13.x.x

test.com is authoritive for 13.11.IN-ADDR.ARPA and 12.11.IN-ADDR.ARPA   I want
sub.test.com to be authoritive for 5.12.11.in-addr.arpa.  This what I did:

a. In 12.11.IN-ADDR.ARPA.zone on name.test.com, I have:

5 IN NS namesub.test.com.
14 IN NS namesub.test.com.

b. On namesub.test.com, I have a zone called 5.12.11.in-addr.arpa.zone which has
the following:

$ORIGIN 5.12.11.in-addr.arpa.
@    IN  SOA     namesub.test.com. hoyoung.test.com. (980926 600 400 2592000 300
200 )
     IN      NS    namesub.test.com.
11   IN PTR    .....
12   IN ....

ON server namesub.test.com, in etc/hosts, I have 11.13.x.x. and
namesub.test.com.  In /etc/resolv.conf file, I have domain sub.test.com.

I only care about reverse resolution.
I can't resolve anything.  What's wrong with the configuration?

Thanks.
btw, the ip ranges and domain names aren't real for security purpose...

Hannah Day