Some cards seem to have issues with the lock ---- they report being write-protected when the switch says otherwise.
To fix one of mine, I switched it 3 times 'unlocked--->locked' cursed at it for 30 seconds, and flipped it to the unlocked position. I was then able to 'cut' the images from the card.
I actually found this solution on the internets and thought, "Pfff, this will never work ... "
But, it did