@Kim Shyuen: It still has the same connectivity problems. I think it would help if you explained, either in words or a 3D sketch, how you intend these rooms to fit together. Usually, it's best for each floor of the building to have its own map, and staircases should correspond -- a staircase from the north edge of the lower floor should arrive at the north edge of the upper floor, so that the upper floor is directly over and supported by the lower floor, which is the usual structure for multi-floor buildings. You can give your building a different structure if you want to, but then it would help to plan out (and show us) the structure first, so that we know what you intend and it's easier for us to point out how you should correct it.