Rubyonrails 奇怪的406 不可接受错误

当我试图通过Javascript点击这个动作时，我得到一个406 Not Acceptable错误:

  def show
    @annotation = Annotation.find_by_id(params[:id])

    respond_to do |format|
      format.html {
         if @annotation.blank?
           redirect_to root_path
         else
           redirect_to inline_annotation_path(@annotation)
         end
       }

       format.js {
         if params[:format] == "raw"
           render :text => @annotation.body.to_s
         else
           render :text => @annotation.body.to_html
         end
       }
    end
  end

这是来自jQuery的，但我在发送之前做了正确的事情:

  $.ajaxSetup({ 
    beforeSend: function(xhr) {
      xhr.setRequestHeader("Accept", "text/javascript");
    },
    cache: false 
  });

以下是我的请求标题:

Host    localhost:3000
User-Agent  Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3
Accept  text/javascript
Accept-Language en-us,en;q=0.5
Accept-Encoding gzip,deflate
Accept-Charset  ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive  300
Connection  keep-alive
X-Requested-With    XMLHttpRequest
Content-Type    application/x-www-form-urlencoded