NFS lock doesn't word

[giuliaccia]

Hi all!
I'm running a NFS server for some tests on my ubuntu 10.04, but my server doesn't do file locking.
If I try to open the same file from different clients it let me do it...but it shouldn't.
I have installed the nfs-kernel-server package on my server and nfs-common package on my clients.
I've also noticed that my server doesn't have a "rpc.lockd" installed...is that the problem?

The output of "rpcinfo -p <myserver_ip>" is:
program vers proto port
100000 2 tcp 111 portmapper
100000 2 udp 111 portmapper
100024 1 udp 38763 status
100024 1 tcp 54295 status
100021 1 udp 52276 nlockmgr
100021 3 udp 52276 nlockmgr
100021 4 udp 52276 nlockmgr
100021 1 tcp 51831 nlockmgr
100021 3 tcp 51831 nlockmgr
100021 4 tcp 51831 nlockmgr
100003 2 udp 2049 nfs
100003 3 udp 2049 nfs
100003 4 udp 2049 nfs
100003 2 tcp 2049 nfs
100003 3 tcp 2049 nfs
100003 4 tcp 2049 nfs
100005 1 udp 60113 mountd
100005 1 tcp 43255 mountd
100005 2 udp 60113 mountd
100005 2 tcp 43255 mountd
100005 3 udp 60113 mountd
100005 3 tcp 43255 mountd

what is wrong?
I hope someone can help me...and excuse me for my poor english!

Thanks

[Rubberman]

NFS and Linux/Unix file locks are advisory only. Unlike Windows, they don't keep you from accessing the files from applications that don't look for the lock.

[giuliaccia]

I didn't know, thank you very much!
Bye!