o que estou fazendo de errado com a seguinte solicitação do Ajax ...?

O link / chamada:

<%= link_to 'Business Analysis', it_business_analysis_path, :remote => true %>

O percurso

match 'it/business_analysis' => 'informationtechnology#business_analysis', :as => :it_business_analysis

O controlador

class InformationtechnologyController < ApplicationController  
  def business_analysis

    render :update do |page|
      page.replace_html 'page_content', :partial => 'business_analysis'
    end

  end
end

A vista

<div id="page_content">
</div>

A parcial é chamada:

_business_analysis.html.erb

O erro

Action Controller: Exception caught

<h1>Template is missing</h1>
<p>Missing template informationtechnology/update, application/update with {:formats=&gt;[:js, &quot;application/ecmascript&quot;, &quot;application/x-ecmascript&quot;, :html, :text, :js, :css, :ics, :csv, :xml, :rss, :atom, :yaml, :multipart_form, :url_encoded_form, :json], :handlers=&gt;[:builder, :coffee, :erb], :locale=&gt;[:en, :en]}. Searched in: * &quot;/home/<user_name>/Websites/<project_name>/app/views&quot;

arece que o Rails está procurando uma visão chamada "update" - por que e como faço para corrigir iss

Muito obrigado! Tom