I don't know what i'm doing wrong. Most of my house plan will have a vaulted ceiling so i usually unchecked the "ceiling over this room" box to remove the flat ceiling. Normally, the ceiling should appear and follow the underside of the roof structure but it doesn't appear. Even rooms that have flat ceilings where i have kept the ceiling box check, aren't being displayed. I have experimented with drawing manual ceiling planes as well but they don't appear either.