[Forum: image floating captions] '-' and '+' signs for rating not appearing at the sides of the ratings counter

I want to positively rate a comment but I see only '0' or '+1' in posts; at the sides of those are links for either '-' or '+' without any image or "floating caption" for mouse-hovering. Those should be available, for many cases, if the user is not able to see the images or the page fails to load those. I see other pictures but not those signs.