I just got one of these and, for some reason, it's not working for me. When connected to my 580, the light on the batt pack comes on like it should. However, it goes downhill from there.
- With the flash set to use all 12 batteries, it functions and recycles like it's only using the original 4 batteries
- With the flash set to use only the CP-E3 for cycling, it doesn't work. It sounds like it's working (whining like it's charging a capacitor), but the flash head never gets charged and can't be used.

