I recently added a receptacle for hanging my TV on the wall. To do it I fished a wire through the wall and attached wires to an existing receptacle that's at a lower level on the same wall.
This is a wall that separated two rooms so there is another receptacle on the opposite end. All white wires and a black wire were joined together, and there was a wire between the two receptacles.
After I added the new wires, the ceiling light fixture in both rooms is not working anymore. I can confirm the bulbs are good, and I also tested it with a line tester and made sure current is reaching the fixture (in the bulb receptor), but no light.
Any other ideas on things I could check?