costanzo.moffa if you look at the folder structure of the extension there are two folders missing. That is why the images don't work correctly. on your pc, go to the extension files and add them
ext/msaulohenrique/wall/images. Add a folder called gallery in the images folder. Within the gallery folder add a folder named 2. (see pic)
The reason the images don't work is because those folders are missing so it has no where to put them.
After the folders are in place, disable and delete data for the extension and then enable it again. The folders should all be there and working correctly so the images will work and the "ghost" images will have been removed.