Rails same piece of code won't work with 3.2

So I have this on the erb:

<%= fields_for camera, :index =>camera.id do |field|%>
<%= field.check_box :alertflag %>

And this on the controller:

 @camera = Camera.update(params[:camera].keys, params[:camera].values)

And it works on one server which have Rails 3.0.9, but for some reason it doesn't work the same way on one server which have Rails 3.2.