strange 406 Not Acceptable on redirect after update

after record create , the redirect to admins_partners_url is working
fine ( :index displaying the page)
but after the update , the record update is performed , but I get this
error

.......`updated_at` = '2012-01-18 14:57:08' WHERE `partners`.`id` = 7
   (10.1ms) COMMIT
Redirected to http://lvh.me:3000/admins/partners
Completed 406 Not Acceptable

same url... on create and update

  def create
    @partner = Partner.new(params[:partner])
    if @partner.save
      flash.now[:notice] = t(:partner_added)
      redirect_to admins_partners_url

  def update
    @partner = Partner.find(params[:id])
    respond_to do |format|
      if @partner.update_attributes(params[:partner])
        flash.now[:notice] = t(:partner_updated)
        redirect_to admins_partners_url

I don't get it ...

[SOLVED] sorry for posting too fast ... pasting my code , I just
noticed that I had a
respond_to do |format| block in my update code ..... removing it did
the trick !

I don't understand yet why .. but I'll do some search about it ....