ActionController::RoutingError (No route matches [GET] "/system/pictures/assets/small/IMG_-_WIN_20141206_09

I'm trying to upload pictures in my rails app, bt it's giving me error:- ActionController::RoutingError (No route matches [GET] "/system/pictures/assets/small/IMG_-_WIN_20141206_09. I don't know where i went wrong.

I try to give :url and :path also and i also upload image of rails logo and move to app/assets/images

$curl -O http://rubyonrails.org/image/rails.png

$ mv rails.png app/assets/images/

My git repository is at: https://github.com/sarahgupta022/book.git

This is my picture.rb

class Picture < ActiveRecord::Base

belongs_to :album

belongs_to :user

attr_accessible :caption, :description, :asset

has_attached_file :asset, style: { 
                      large: "800x800>", medium: "300x200>", small: "260x180>", thumb: "80x80#"
                      } , :default_url => "/app/assets/images/small/rails.png"


  validates_attachment_file_name :asset, :matches => [/png\Z/, /jpe?g\Z/, /gif\Z/]
 validates :asset, attachment_presence: true



  def to_s
    caption? ? caption : "Picture"
  end                    

end

This is my views/pictures/index.html.erb

<p id="notice"><%= notice %></p> <%= page_header do %> <% if signed_in? && current_user == @user %> <%= link_to 'Add Picture', new_album_picture_path(current_user, @album), class: 'btn pull-right' %> <% end %> <h1><%= @album.title %></h1> <% end %>

<ul class="thumbnails"> <% @pictures.each do |picture| %> <li> <div class="thumbnail"> <%= link_to image_tag(picture.asset.url(:small)), album_picture_path(@user, @album, picture) %><br /><br /> <div class="caption"> <% if picture.caption? %><%= picture.caption %><br /><br /><% end %>

            <%= link_to 'View full size', album_picture_path(@user, @album, picture) %>

            <% if can_edit_picture?(picture) %>
            <%= link_to "Edit", edit_album_picture_path(@album, picture) %>
            <%= link_to "Delete", album_picture_path(@album, picture), method: :delete, data: { confirm: "Are you sure?" } %>
            <% end %>
            </div>
            </div>
        </li>
<% end %>

</ul>

Greatly appreciate any help. Thank you!