@vvillenave : Voici ce qu'on peut lire sur le site :

"For now, Open Attribute only works on pages with Creative Commons licenses and if the license code doesn’t include complete attribution information, Open Attribute might not be able to get the full attribution for you. In the future, we hope to make Open Attribute work with other open licenses like the GNU GPL, and to make it smarter about pulling attribution information even when that that information is hard to find."

Donc patience :)