Architect Archive

I am trying to decorate my PA Hall using the same technique as I did with my large house, by dropping an item on the stiars then moving it to place it where I want to float it. The problem I am running into is that when I drop anything on the stairs and move it, when it gets to the doorway I get the "invalid" position when I try to move it through the door. I have tried dropping things lower and moving 1 space at a time, does anyone know if there is a workaround for this...or if there is a site that covers home decoration? Thanks