Shutting down a remote computer

Hi,
I have to computers which are connected together by a peer-to-peer network without any hubs.
I want to shut down one of them from another one from command.com environment but the following function doesn't work: shutdown -m \\Pc2
Pc2 is the name of the computer which must be shutted down.
I tried it by IP address to but it doesn't work.
how can I do that?!
:-/