You can only put your house on a lot that is same size or bigger than the lot the house was built on. So if your house in the bin was built on a 50x50 lot, then you cannot place it on a lot that is any smaller, and so then the choice to build there is taken away from you. I'm guessing that this may be your problem. I would try to actually bulldoze the lot and then place a big enough lot there to put the house on.