Save Jquery sortable state to DB

[eluser]Ludovic-r[/eluser]
Ok now I can't access to my $.post data from my Controller. I have this :

var order = $(this).sortable("serialize");
$.post("http://localhost:8888/codeigniter/index.php/admin/order", order);

And in my controller this :

function order()
{
$order = $this->input->post('list_item');

echo $order;
}

I echo it just to see if it works, I know it's not its place, but unfortunately it doesn't work any ideas?