Got an ishoot pt04 trigger and receiver. I assumed this would work with my D50 and SB400, just not able to adjust anything. Is there any reason it won't fire (as in it's faulty) or are they not compatible at all? I do have access to another, OLD flash that works on my D50 that I can borrow from my grandad, as it's from his old film days, I have no idea of the spec on that. The trigger/receiver box just says compatible with nikon so I just assumed it would fire!