Adding Images to the comprofiler/gallery/canvas

I can add images to the comprofiler/gallery/canvas folder but when I go to the profile to update a background image, I can only see 2 of the uploaded images? There seems to be a placeholder for each of the 4 additional images and I can select the blanks and they will replace the existing image but nothing displays on the profile? Is there a size element that I may be missing? The images are a combination of jpg and png.

You need to be sure you supply a full size and a thumbnail size image. So for example lets say my image is "stars.jpg" then the thumbnail should be smaller and named "tnstars.jpg".