Sometimes I draw a floorplan of my house and ask if the lost object is in the room I'm pointing to on the diagram, and just go through all the rooms.
Other times I just walk through the house and ask if the item is in the current room or not.
If my System says it is in a room, then I ask if the item is on the left or the right, and keep drilling down until I find it.
There are times when I believe my System is wrong because I already looked in the location specified, but to date, my System has always been right. Usually it is my attitude that stops me from finding an item--I don't believe the item is where my System says it is (I'm not being neutral and open).
Another thought...ask if you have poltergeists in the house, and if you do, ask for them to be removed before you dowse for your lost item, and let us know if you find it.