digital camera mount

Hi everyone. I have a Nikon Coolpix 775 and a Lexar usb cable. On my computer with 8.0 at home I can do: mount -t vfat /dev/sda1 /mnt and see my photos under /mnt. On my computer with 8.0 at work I get the error: mount: /dev/sda1 is not a valid block device. Any ideas anyone? Thanks, Steve.