Try these things:
1) Turn off the firewall on both computers. If you are using a third party firewall disable it.
2) Make sure you have "turn off password protected sharing" checked.
3) Try them both wired to the network. If they are wireless to the network they may be some issues.
4) Can you ping from one laptop to the other?
5) Make sure on laptop is the Host (master) and the other is the client (setup).
Good Luck,
Jim