Weird behavior in admin theme

Activating this module cause admin theme to be broken.

Admin theme is a Garland sub theme using admin_menu module. While navigating in the site as administrator I noticed Admin Menu were not displayed on some page. When it occurs, admin theme fallback to Garland.

Here is some trace :

• Advanced CSS/JS Aggregation is activated.
• http://www.example.com/admin/settings/advagg : everything is fine
• http://www.example.com/admin/settings/advagg/info : problem occurs.

Browser console output a 404 error on sites/all/modules/admin_menu/admin_menu.css.