Vip, facilities cannot be set to be closed completely. The best you can do is set them to be closed to crewlist. So as Foop said, make sure your on the crewlist, though if they want you to do something with the mine, most likely you will need ot be operator.
Also, just incase you already have got access, make sure you are in the Entrance Room of the ship of vehicle your in, and that you are on a square next to, or on top of the mine - you cannot enter it from across the city obviously.