Hi Simon
yes as Matt has said I use command mode at times mostly if i want some very low on camera flash too, I also use wireless remote triggers.
what you describe sounds very much like already mentioned by Paul the Pre flash triggering the lights before the shutter opens Im a Nikon user and not sure of your camera but I would try sutting off any Pre flash and go from there if you have tried this already then to Go Full manual with your settings,
all the above fails and the flash head setting James has given, then contact the makers of the flash heads your find they are always more than happy to help and at times the best people to ask
best wishes
and good luck
James.