Problem with nested forms in Rails 3 with remote true

I have an index page for people, on this page there is a button 'add
person' that shows a hidden form when you click on this button.

The problem is, when I submit, the nested attributes for pictures are
not send as parameters. When I just use the normal form in the url
'person/new/' then it works, but when showing the hidden div, I render
the same form so that can't be the problem. Somebody who can help me?
Here is my code of the views, model and controller :

http://pastie.org/1405410