MacBook Pro (unibody) not detecting ethernet cable

MacBook Pro (unibody) not detecting ethernet cable

I've got a 15 inch unibody MacBook Pro. So far I've been using WiFi and everything worked well. I've just switched to wired network and the machine doesn't seem to detect the network cable when it's plugged in. It works when I use the same cable with a PC, so router and cable seem to be OK.