I drive a 2014 vw touareg gas sport lux with factory installed hitch and factory towing harness package. No factory installed 7 pin socket came with the car. I purchased *a Pollack 7 pin socket(PA66-GF30) on eBay to fit the vw factory harness. Even called pollak tech support and they said connector would work. Removed the cover and inserted the socket. Fits perfectly. I purchased a 7-Pole Round to 4 Flat Adapter to mate with the 7 pin socket. This adapter only has 4 active pin slots *with 4 flat trailer connectors on the opposite end. I have a small utility trailer i use around my yard and haul pine bark. No trailer brakes,I just need turn signals and stop lights. Rewired trailer with new 4 flat pin wiring and new tail lights. I get continuity on all the wiring on my trailer. Hooked up trailer to touareg. Right tail(curb side) blinks and stop works fine. Left (driver side) stop and blinker does not work. Bulb is OK. *Message on dash says to check driver side tail light. Rechecked trailer wiring and it is OK. Went out and purchased a new Hopkins 7 blade to 4 pin adapter with LED test lights. Removed trailer from from hitch then plugged in new Hopkins adapter. Running lights test light glowed, and so did brake and turn signal light on curb side. No test lights glowed for driver side brake light and turn signal without trailer coupled. Same results with trailer coupled to hitch. *Same message appeared on dash to check left side lights. Any suggestions on what is wrong? Bill