Make sure only one card is inserted at a time. PictureMate does not read from multiple cards at once.
Make sure your photos are in JPEG or Uncompressed TIFF format and taken with a DCF-compliant digital camera. If you’re using JPEGs, make sure they are non-progressive. PictureMate can't read progressive JPEG files or RAW files.
Make sure the resolution of your photos is between 80 x 80 and 4600 x 4600.
Make sure the memory card you're using was formatted by your digital camera and not by a computer. Also, always use your camera (not a computer) to delete files from the card. Otherwise, the card may not work correctly with your camera and/or PictureMate.