Why "Component was not inserted" error message can appear?

Q: Dear Support,

When I tried to publish and insert the Visual Lightbox into a page I got an
error message like this "Component was not inserted" I tried several times at it keeps having the same error message and the page did not show the visual lightbox.

A: This error usually happens, if there are mistakes in marking on your page or this page is
empty, it should be at least one visible element, for example <p></p>, <div></div> or,
probably, you don't have rights to edit this page.

Please, check it.