I'm having a problem with one of my flashes, its a vivitar 285hv. I'm using a Cactus V4 setup for off-camera flash, and it isn't firing with it. The transmitter and reciever are both lighting up, I tried with another flash and everything worked fine. I also tried my 285hv right on my camera's shoe and that worked fine as well. Any help would be awesome. Thanks everybody.