because my card reader is write protect.
i had this problem too. theres a little switch on the side or somewhere on it, make sure it is on the unlocked position
In the image below, notice the yellow switch on the left side of the card. If that is pushed down in the notch, then the card would be write-protected. To unlock it, just push that up to the top of the notch. google.ca/imgres?imgurl
