Just as a sanity check, have you checked to make sure the write protect slide on the side of the SD card is in the position closest to the metal contact tabs?
Hello,
how do U remove write protection from an SD card that I did not add it to?
I just had the SAME problem and discovered the itty bitty slide which had worked itself down on the side of the card. Move it up.
Good luck,
mensabrite @ aol.com