My guess is you've accidently lock the card when handling it fitting in camera. Remove the card and check the slider on the side of the card, Lock is written on the face of the card next to the slider lock being at the narrow end of the slider position arrow, the slider needs to be at the wide end of the arrow [looking at my SD card]. Once un-locked replace it in camera and carry on snapping. Don't worry you're not the only one I've done it, and one time got angry missing a shot then realised I hadn't switched on the camera, sometimes our brains get puddled with new fangled things, never had this problem with 'The Box Brownie' changing film under a blanket with some clown pulling it off and ruining the film.
Bob, October 2010
