left tail lights wont work!

i just installed new tail lights lenses on my honda civic. i replaced all four of the separate pieces to the tail lights (left/right outside tail light and left/right taillights on the the trunk). and then i put the bulbs back into the taillights and put the carpeting back over it. i thought the installation went smoothly but when i got back home i noticed that when i pressed the button to lock my car as i was walking away, the left tail light did not flash when the other three did. so i took the whole left unit apart and looked at the bulbs and they are not burnt out. i checked all fuses, and i even checked to see if the wires were grounded still and the all the other wires seem to be fine. i made sure to push the bulbs all the way into the bulb holder and everything seems fine. but both bulbs from the left outside tail light unit will still not work! i have no clue whats going on. maybe im overlooking something small, or im just not close enough attention. can someone please give me some advice on what to do? ive run out of ideas. any help would be much appreciated.

Do you have a meter or a test lamp ?? You will need to check for voltage present and confirm ground is working. Should be a simple fix.