more than one photo on a product

The first successful product images, all begins with rustic_blue_6x6 on file names. Numerically sorted so they display according to the numbering.

in "large" directory. I tried to put them in medium directory but the photos won't show up, not even one, even though the instruction says there is ONE medium image displays.

But wait! I deleted images in "large" directory and they still display. The program reads images in image directory, not in "large."