I have a sketch with a micro SD card reader. It works with a SanDisk card but not a Sony card. No changes made to hard ware or software between the cards. I re-formatted the Sony card (the one that does not work) with the Windows format untility (card still not readable) and later with the SD association's format utility... still can not be read. Any ideas on why one brand of card will work with the SD card reader but not the other brand? BTW: Both cards work just fine in my non-Arduino consumer electronics. Thank you very much in advance.