Going from a 256mb card to 8G & camera.

Going from a 256mb card to 8G & camera.

I have been using a 256mb card in my cannon powershot sd450...upgrading to an 8gb card.....the camera is stating that the card is locked..the card is not in the locked position...inside the camera, there is nothing protruding to flip the lock switch. Why won't the new card work...the new card is a Kodak brand card.