I went to instal a taillight for a friend and it didn't work. It was the passenger side light on the trunk. Is there any reason why this wouldbe the case? I did not check before hand to see if they worked so maybe that was the issue. Aren't both lights independent of each other anyways? Also, both reverse ligths didn't work either...even after I re-installed the old light (cracked lense)

535i and 525i tails are identical, at least with the same model year. Maybe the 95 uses different bulbs? :dunno And what lights do you refer to when you say "both lights independent of each other"?

both sides (driver and passenger) lights