maybe it does work on response, ie. when queried, the energy of the question fuels up the transmitter to to send reply.
what would happen if I scan it with the full range of frequencies?
second possibility, it's batteries are down, and need to be replaced, or reloaded (is there a way to do so?).
other than that the badge would have to be recognized on visual, so one would need to carry it on visible spot or put before the reader while opening the doors. (are there any badge readers on the doors/stairs?)