can't mount "/" partition

[Nabin Limbu]

Hi,

I have 2 partition "/boot" and "/" only. I can mount any folder inside "/" partition via nfs without any problem but can't 
mount "/" partition.

eg:

mount 192.168.0.1:/var /mnt ==> works

but,

mount 192.168.0.1:/  /mnt ==> doesn't work

Error message shown:
mount: 192.168.0.1:/ failed, reason given by server: Permission denied

Is there any security feature that denies me to mount "/" partition via nfs or am I missing something?

Regards
Nabin Limbu