cactus v5 question: trigger shutter and flash?

I'm new to remote triggering so this may be a noob question but I have 3 cactus v5 transcievers. I set up one on my flash (yongnuo 560) and one with a cord to fire the shutter. I can execute both using the third but they don't sync. the shutter releases after the flash so the image has none of the light in it.

any suggestions? I'm using a Lumix GF1 and my present feeling is that it's just not fast enough (?).

thanks!