I translated a part of chat plugin into french with pot

Hello,
I translated a part of chat plugin into french with pot file.
I put chat-wordpres-fr_Fr.po and chat-wordpres-fr_Fr.mo into plugin/wordpres-chat/languages.

My wp config is in french withe those values : define('WPLANG', 'fr_FR');

But everything keeps in English.

Thanks for your help.

PS : I work with 3.5.2,
I refreshed my pages a lot of time, and deleted my cache, no change