My secondary pic wasn't showing but then I realized I didn't organize my pics properly. I followed this link >> How do I add multiple images to a product?

And in case you need to know more about sizing (because your lightbox image is bigger than standard pic size..), check out >> Image Preparation - How-to

Fortunately worked for me, I thought it was annoying to organize in this fashion, but it ends up being tidier and clearer in the long run.

Repost if it works/doesn't work, good luck
Tat