Message Display

I have a 256MB memory card for my camera. I have not taken many photos. Even at the lowest picture quality setting of 640, the camera reads that I only have 146 images to take.

When I try to review what is in the camera, I receive the message "No Valid Image to Play." The instruction manual explains that the message means. However, I was not able to find anything that tells what to do to increase the number of available photos from 146 to more. This problem happened once before with a different sized memory card.

I tried to delete everything but each time I depress the "review" button, the "No Valid Image to Play" message appears. Is the problem with the memory card or the camera?

Thanks.