Whats going on with this Archway placement?

I tried that, Bulldozed everything built using the room tool.. then just the wall tool.. and in the right room especially wouldnt let me place the archway.. the room to the left.. it would only let me place on the wall at the far left point of the wall not the middle. Nothing above had been built which is why its so confusing.. Keep in mind though for the one that isnt working right is the Rightside room is 4 x 3 not 4 x 4