BIND Server unable to resolve outside names

[amacdos]

Hi there , I am having problem with my internal BIND DNS server . 
I have setup, it can resolve local names , including other internal
DNS servers
But unable to resolve outside names . When did an nslookup , 

> hp.com
Server:  test.com
Address:  100.0.20.30

Authoritative answers can be found from:
(root)  nameserver = a.root-servers.net
(root)  nameserver = h.root-servers.net
(root)  nameserver = c.root-servers.net
(root)  nameserver = g.root-servers.net
(root)  nameserver = f.root-servers.net
(root)  nameserver = b.root-servers.net
(root)  nameserver = j.root-servers.net
(root)  nameserver = k.root-servers.net
(root)  nameserver = l.root-servers.net
(root)  nameserver = m.root-servers.net
(root)  nameserver = i.root-servers.net
(root)  nameserver = e.root-servers.net
(root)  nameserver = d.root-servers.net
a.root-servers.net      internet address = 198.41.0.4
h.root-servers.net      internet address = 128.63.2.53
c.root-servers.net      internet address = 192.33.4.12
g.root-servers.net      internet address = 192.112.36.4
f.root-servers.net      internet address = 192.5.5.241
b.root-servers.net      internet address = 128.9.0.107
j.root-servers.net      internet address = 198.41.0.10
k.root-servers.net      internet address = 193.0.14.129
l.root-servers.net      internet address = 198.32.64.12
m.root-servers.net      internet address = 202.12.27.33
i.root-servers.net      internet address = 192.36.148.17
e.root-servers.net      internet address = 192.203.230.10
d.root-servers.net      internet address = 128.8.10.90
>

Can anyone tell me what's happening , and why it can't resolve as per
normal.

My Internal BIND server is pointing to our ISP dns servers.and it goes
through a Firewall.

Looking forward for a reply

Thanks