2 working 1 not

I am installing a 3rd computer onto an already existing network of 2 pc’s.
I have a intel inbuisness 4 port fast hub, ports 1 and 2 are taken by the already existing computers. I plug in the 3rd pc and the indicator light for the 3rd port does not turn on. I have tried swapping ports and cable. The nic card in the 3rd computer is a realtek8029 and it works fine on another network connected with a crossover cable with another pc.
PLEASE HELP!!!!!!!