Redmine › Download Button

Hi,
I use latest Redmine 2.3.x from their SVN repository and latest version of “download-button” from http://svn.s-andy.com/download-button

I tested in development mode on Ubuntu.

Here is that I see in log on accessing of any path on localhost, even http://localhost:3001/

Missing template, responding with 404
  Rendered common/error.html.erb within layouts/base (0.8ms)
Completed 500 Internal Server Error in 1018ms

ActionView::Template::Error (Missing partial download/sidebar with {:locale=>[:en], :formats=>[:html], :handlers=>[:erb, :builder, :rsb]}. Searched in:
  * "/mnt/disk/Devel/RoR/redmine-2.3/app/views" 
):
    47:     <div id="main-menu">
    48:         <%= render_main_menu(@project) %>
    49:     </div>
    50:     <% end %>
    51: </div>
    52: 
    53: <div id="main" class="<%= sidebar_content? ? '' : 'nosidebar' %>">
  lib/redmine/hook.rb:111:in `block in render_on'
  lib/redmine/hook.rb:61:in `block (2 levels) in call_hook'
  lib/redmine/hook.rb:61:in `each'
  lib/redmine/hook.rb:61:in `block in call_hook'
  lib/redmine/hook.rb:58:in `tap'
  lib/redmine/hook.rb:58:in `call_hook'
  lib/redmine/hook.rb:158:in `call_hook'
  app/helpers/application_helper.rb:1161:in `view_layouts_base_sidebar_hook_response'
  app/helpers/application_helper.rb:1157:in `sidebar_content?'
  app/views/layouts/base.html.erb:50:in `_app_views_layouts_base_html_erb__872624873_94244800'
  app/controllers/application_controller.rb:397:in `block (2 levels) in render_error'
  app/controllers/application_controller.rb:395:in `render_error'
  app/controllers/application_controller.rb:383:in `render_404'

Do I miss something in installation?