Problem with JSON format - Help and explanations needed

Hello
I don't understand why my datas does not display, and I have the classical "Requested unknown parameter 0 from the datasource". What is wrong in my JSON format ?
I used DataTables debugger result is here : http://debug.datatables.net/eduleh

Any help would be appreciated.
If it can help I'm using Rails 3.2.11 with the datatables gem (https://github.com/rweng/jquery-datatables-rails) on windows8

Cheers