I steal/loot keys from people and then use them on the required door, for example Lucas Simms, killed him went up to the shack which now reads "empty house requires key" press E and its not opening says it requires a key. Its doing this for everything, the keys just aint working, any suggestions? `im on PC.

This needs to be moved to Cheats & Hints....

If you're looting a key from Lucas Simms, then that key will be for his own house in Megaton. If you want to get into the empty Megaton house (on the left as you enter the Megaton front gate) then the requirement for that is very different. Is that what you are trying to do?

Once moved to Cheats & Hints, we can give more detail.