If you have more than 9 pictures in your gallery, you should number them with two digits, otherwise it's gonna fuck up the order in most image viewer programmes.
So don't go (1), (2)....(10) in your file names, but (01), (02)....(10) instead. How fucking hard is it?
People these days don't even draw hentai anymore they just churn out fucking 300 AI slides and can't even be bothered to properly name the pics.