Electrical issue

My car has a small light in the drivers side door and the passenger side door. The drivers side door works fine however the passenger side door light does not work. I tried replacing the bulb, but even the brand new bulb did not fix the problem. I tried the same bulb in the drivers side and it worked so the bulb itself is good. What can the problem be? If the drivers side works that means the use is good right? Or is their a separate fuse for the passenger side door? If not the fuse I guess that means I either have a bad socket or a wiring problem right? I am trying to figure out the most inexpensive way to resolve this problem. Please help, your advice is greatly appreciated. Thank You.