I had this same issue, tried multiple cards, multiple PC's/Card Readers without much luck. I seem to recollect I finally got a card that would not work to work by formatting (in Windows) it to NTFS or FAT16 first, then going back and formatting it to FAT32 and the putting the file structure on it using the Unitronics utility. Give this a try and see if it works and post your results so we can see if this method works more than once...