I've had this happen 3 times recently: having a 580EXII on a stand with a PW PlusII connected to it & my 5D MKII with a PW PlusII on it, the flash keeps failing to fire. Batteries in everything are always fully charged. Not an issue of not giving the flash time to recycle. I can't pinpoint the problem, I'll try everything (turning the flash off, then on, turning the PWoff then on) & suddenly it'll start working again, sometimes not failing again but sometimes happening again. Suggestions on what to check? Could it have anything to do with my camera settings? I shoot in Manual, flash is set to manual.


