will_paginate: pagination links are wrong

I put everything in a pastie to make it a bit more readable:
http://pastie.org/593379

This is the gist:

Will_paginate doesn't play quite nice. The first result set is fine,
and when I click on one of the paginated links, it returns the following
error:
Couldn't find DictatedExam with ID=filter_widget
observe_field triggers filter_widget which calls the paginated search..
Which is then rendered in a partial.

Why do things simple when you can do it complicated, right ?

Addendum:

This is what the links look like.
I have no idea what they're -supposed- to look like.

http://localhost:3000/dictated_exams/filter_widget?page=4

AND FIXED!
I followed http://jellofishi.com/blog/?cat=3

I created app/helpers/remote_link_renderer.rb

class RemoteLinkRenderer < WillPaginate::LinkRenderer
  def prepare(collection, options, template)
    @remote = options.delete(:remote) || {}
    super
  end

  protected
  def page_link(page, text, attributes = {})
    @template.link_to_remote(text, {:url => url_for(page), :method =>
:post}.merge(@remote))
  end
end

And then in the environment.rb I added, after the Initializer block:

require "will_paginate"
WillPaginate::ViewHelpers.pagination_options[:renderer] =
'RemoteLinkRenderer'

My will_paginate has become:
<%= will_paginate dictated_exams, :params => {:date => date },
    :remote => { :update => 'filter_counts'} %>

And now it all works..