What port are you using for the uplink? The hub will have port for this. If you are using the uplink port for a computer you will only get one way traffic.
Does your hub have a midi - midi-x switch?
If not you will need to use a crossover cable to link your hub with the rest of your building.
Other than that, unless you are using very old network cards that only use a 10 base t connection and your hub is only 100 base then your hub is faulty.