Not if you are useing intel macs. At least this is what apple says here:
http://support.apple.com/kb/HT2274
OP: does the cable connection get detected? i mean does the ethernet connection shows up as connected in the Network Pref panel? That would exclude a cable problem at least.
Then you should check which IP addresses each mac has: are they on the same subnet? Are the IP the same except the last number?