I am getting an error message when using long exposure and rear curtain sync with my 60D and 580EXII. I was trying to take a long exposure set on bulb, and had the flash go off right before the shutter closes. I kept getting an error message. The message popped up "error, try removing battery and replacing it". Also, the images would not record on the card. Has anyone had this happen? I haven't tried recreating what I was doing but, now the camera is working perfectly.