There is always the possibility of buying a defective part. I would turn the headlights (or parking lamps) on at the headlight switch, and poke the brown wire with a test light and see if it is getting power. If the brown wire is hot at that end, and not at the other... you know the problems is somewhere in the middle. The wires run down the drivers side of the car and enter the trunk behind the drivers side trunk kick panel (i hope that made sense), and loop around the back. So if your looking at your car from a birds eye view, the wiring schematic would be in the shape of an L. If your brown wire is hot at the switch AND hot in the rear, I would check your grounds. You said your brake lights work if i recall correctly, and your brake lights are powered through a light blue wire, so that would explain why those work and the parking/tail lights don't work. And your turn signals work because those get their power from the yellow and green wire. So it sounds like your brown wire is the cause... or.. the connection at the switch is no good. Hope this helps.. good luck!
Oh ya... yer marker lights feed off the brown wire too!