Multiplayer not working on the same network?

When I open my server, I can join, but on the other computer In my network can't connect.
HOW TO ACHIEVE:
1. open the server for 1.7.2,1.7.4 or 1.7.5.
2. open minecraft
3.join the server.
on the other computer :
1. open minecraft
2. when server is ready go to multiplayer
3. wait for connection.
IT SAYS
1.on mine: I have joined
2. on the other computer: No connection. (The internet is working, and correct ip address)
SORRY NO SCREENSHOTS