I am trying to hook my Canon EOS 20D up to my 17" MBP. The card reader I used to use was built in to my old printer that I don't use anymore. So I am using the USB cord to hook the camera with the CF card inside to the MBP. I have turned the camera on after I plug it in and nothing happens. I know the USB port works, other peripherals work with it. I know the cord works.... I use the sam cord for other items... What am I missing?