I have a Wein Safe Sync hot shoe to PC adapter. i have used it on my G5 to sync my studio lights (with a Quantum Radio Slave) successfully. I tried to use it with my Canon 580 in Auto mode (not ttl) and it will not fire. The 580, in Auto mode, is connected by it's PC terminal to a PC cord connected to the Wein, mounted in the G5's hot shoe. I also tested the flash in Manual mode and had the same thing happen...no flash fires. If I disconnect the Wein from the G5's hot shoe, I can manually trigger the flash with the Wein test button, but mounted on the camera, it won't fire either with the test button or with the shutter. Any thoughts?