Registration not working

Hello,

When a new user try to register, the loading animation doesn’t stop and he never receive an email with his login/password information.

Here is a screenshot : http://i.imgur.com/oINRy6w.png?1

My website is : http://www.ades-sorbonne.fr/ ; Registration works with wp-admin.
Everything is checked to let the user register (in Settings > General and “Ajax Registration” is checked in the widget).

I don’t know how to solve this problem.

Thanks.

https://wordpress.org/plugins/login-with-ajax/