tail light and license plate light not working

[colorado]

both park lights and headlights, fog lights, brake lights, reverse lights and all signal working. no park(tail lights) and license plate light in the back. replace all bulbs, replace the fuse for park light, tried a new relay. still nothing. removed all panel in the back and inspected all wires. can't see any obvious problem. no corrosion on the ground that i've seen so far. look at a wiring diagram and for what i seen its on the same circuit going to the fuse in the car. got power to that fuse. what am i missing? really need help on this on. thanks