Q. I already have money on my comet card, but the machine says I have a zero balance.
It could be several things:
1) Make sure you correctly check your balance via the add value machine or through the GET Portal.
2) Some departments on campus already provide funds to the comet card (e.g. JSOM), however, those funds do not work in the library. Those funds will only work in the labs associated with that department.
3) If you just put money on your comet card, but still shows a zero balance, go to the comet center and they'll refund the lost amount.