I've tried firing it from my hassy, F, F6, Yashica, DSLR, and a copal 3 using both the sync cord and the hotshoe part. I thought it was possible that the triggering voltage simply wasn't enough, but I even tried a much smaller flash from my rollei 35 and it still didn't fire. While some degree of build inconsistency is to be expected from a cheap product, I've tried 4 of these and none of them work! that seems a little ridiculous to me...

Perhaps the "for Nikon" set will only fire nikon speedlights?! I broke my SB-600 a while back and still haven't gotten a replacement...