Every time I swap chips I format the card in the camera. It deletes all the old photos and I know it is formatted to that device. I have never had a problem. In the past in a cheaper camera I used to have, if I tried to view the photos in my digital camera is would show as no photos, but once I put it in my laptop they would be there. The pictures may be on your card still also, sometimes they can be saved in a wierd folder on the chip, you just have to dig for it.