Small, medium, large versions of product images--I've gotten mixed messages

Directory reads not in alphabetical order. It is rather equivalent to 'unsorted' form of the list, with folders scattered in midst of files. Yes, that is the only answer that can explain the results you were getting, so I kind of expected it, just didn't know.

Hello, I have the same problem as many, I have read many post and did what I'm supposed to do but with the wrong result, maybe I'm missing something.

My images are as follow:
/images/catalog/picture.jpg
/images/catalog/picture_01.jpg
/images/medium/catalog/picture_01_MED.jpg
/images/large/catalog/picture_01_LRG.jpg

My MED and LRG image doesn't show, please take a look at http://sanpojewelers.com/index.php?main_page=product_info&cPath=6_15&products_id=86
Thank you in advance,
Sam

Is there some reason that you don't have

/images/medium/catalog/picture_MED.jpg
/images/large/catalog/picture_LRG.jpg

The fact that the main product image medium/large versions don't exist might cause the additional product images module to not look for others ...

For starters, /images/medium/catalog/picture_01_MED.jpg is irrelevant since additional images never use the "medium" version, only the small and large.

/images/medium/catalog/picture_MED.jpg should display as the product main image in the product info page if it exists. If not, the base ("small") image will display; in either case, the large image should pop up on click. This is what happens with your example product. The small version of your additional image displays on the page, and the large version pops up.