title: uninitialized constant - totally lost with this in Rails
body: <p>I'm trying to upload a file  to a form with Carrierwave, but everytime I run my rails server I am met with the following message:</p>
  
  <p>NameError in ListingsController#index</p>
  
  <p>uninitialized constant Listings::ImageUpLoader</p>
  
  <p><strong>Extracted source (around line #2):</strong></p>
  
  <pre><code> 1.    class Listings &lt; ActiveRecord::Base
   2.         mount_uploader :image, ImageUpLoader
   3.   end
  </code></pre>
  
  <p>Rails.root: C:/Sites/redemo</p>
  
  <p>This is what my error log says</p>
  
  <pre><code>Started GET "/listings/1/edit" for 127.0.0.1 at 2014-06-06 20:09:16 +0100
  Processing by ListingsController#edit as HTML
  Parameters: {"id"=&gt;"1"}
  [1m[36mListing Load (0.0ms)[0m  [1mSELECT "listings".* FROM "listings" WHERE        "listings"."id" = ? LIMIT 1[0m  [["id", "1"]]
  Rendered listings/_form.html.erb (111.0ms)
  Rendered listings/edit.html.erb within layouts/application (121.0ms)
  Rendered layouts/_header.html.erb (0.0ms)
  Rendered layouts/_footer.html.erb (0.0ms)
  Completed 200 OK in 248ms (Views: 240.0ms | ActiveRecord: 0.0ms)
  
  
  Started PATCH "/listings/1" for 127.0.0.1 at 2014-06-06 20:09:20 +0100
  Processing by ListingsController#update as HTML
  Parameters: {"utf8"=&gt;"✓",    k
  </code></pre>
  
  <p>        [1m[35m (0.0ms)[0m  rollback transaction
            Completed 500 Internal Server Error in 19ms</p>
  
  <pre><code>ArgumentError (wrong number of arguments (2 for 1)):
    app/controllers/listings_controller.rb:45:in `block in update'
    app/controllers/listings_controller.rb:44:in `update'
  
  
  Rendered C:/Ruby200/lib/ruby/gems/2.0.0/gems/actionpack-   4.0.0/lib/action_dispatch/middleware/templates/rescues/_source.erb (2.0ms)
  Rendered C:/Ruby200/lib/ruby/gems/2.0.0/gems/actionpack-4.0.0/lib/action_dispatch/middleware/templates/rescues/_trace.erb (3.0ms)
  Rendered C:/Ruby200/lib/ruby/gems/2.0.0/gems/actionpack-4.0.0/lib/action_dispatch/middleware/templates/rescues/_request_and_response.erb (2.0ms)
  Rendered C:/Ruby200/lib/ruby/gems/2.0.0/gems/actionpack-4.0.0/lib/action_dispatch/middleware/templates/rescues/diagnostics.erb within rescues/layout (146.0ms)
  </code></pre>
  
  <p>I'm totally lost on this one.  Any advice please?</p>