"Add media" button doesn't work in front-end

Hi,
I’ve installed acces press anonymous post in order to publish articles directly in front end and to permit the same things to users.

Everything’s ok : people have the rights to publish media and button is showing.

However, this button doesn’t work ! I tried with the link in the tinymce editor and it’s impossible too although all other things are working.

How-to make this button working in front-end (everything’s ok in back-end) ?