Problem when I try to load certain images

When I try to load multiple images such as these ones :
http://sharkmapp.com/wp-content/uploads/2016/07/cities-29.jpg"
http://sharkmapp.com/wp-content/uploads/2016/06/baccara.jpg"
http://sharkmapp.com/wp-content/uploads/2016/06/crazy-horse-facade.jpg"
http://sharkmapp.com/wp-content/uploads/2016/04/on_the_radio_bar_danang_05.jpg"
"http://sharkmapp.com/wp-content/uploads/2016/07/horse_PNG2545.png"
"http://sharkmapp.com/wp-content/uploads/2016/07/Space-Backgrounds-Wallpaper-fullsize.jpeg"

Only 4 of them are added and not even in the same order. Is there issues with file dimensions or type ?

Thanks,
Vincent