Occasionally, when I first started using Adobe Bridge, I'd plug in my camera (I haven't got a card reader yet), try to "Get Photos From Camera", and I'd get the following error message when the wizard tried to pull the photos off my 350d / Rebel XT:
"Cannot obtain all files from this device. Please ensure the device is connected properly, or that the battery is charged."
Thinking that my camera's battery was a little on the low side, I'd just pop in my spare, and everything would work fine - usually. However, sometimes even with a freshly charged battery they'd be a problem. I thought it was just my old Canon Battery (the original that came with the EOS 350d when new), but what I've found is an easy work-around.
When you go to retrieve your photo's, after Adobe Bridge has made contact with your camera, let it generate ALL of the thumbnails before you click "Get Photos".
Now Adobe Bridge works for me every-time, low battery or not!