If you apply a vapor barrier, then insulate, you have to make sure that insulation doesn't keep the the vapor barrier so cold it can fall below the dew point of your ambient temperature/humidity. If you condition the space, the warm humid air can seep around insulation gaps and condense on the surface of the vapor barrier.

Had this type of thing happen on a big commercial project. Guy thought he was being smart adding fiberglass batt insulation on top of a suspended ceiling. This insulated the interior space but also insulated the metal roof deck above from the interior heat, but allowed the water vapor/humidity created by the occupant load to still seep into the above ceiling space thru light fixtures, gaps etc. where it promptly condensed on the now colder metal deck and dripped back onto the suspended ceiling - to the point he though he had dozens of roof leaks.