title: Plural for fields_for has_many association not showing in view
body: <p>Currently, an <strong>Item</strong>  <em>belongs_to</em> a <strong>Company</strong> and <em>has_many</em> <strong>ItemVariants</strong>.</p>
  
  <p>I'm trying to use nested fields_for to add ItemVariant fields through the Item form, however using :item_variants does not display the form. It is only displayed when I use the singular.</p>
  
  <p>I have check my associations and they seem to be correct, could it possibly have something to do with item being nested under Company, or am I missing something else?</p>
  
  <p>Thanks in advance.</p>
  
  <p><em>Note: Irrelevant code has been omitted from the snippets below.</em></p>
  
  <p><strong>EDIT:</strong> Don't know if this is relevant, but I'm using CanCan for Authentication.</p>
  
  <p><strong>routes.rb</strong></p>
  
  <pre><code>resources :companies do
    resources :items
  end
  </code></pre>
  
  <p><strong>item.rb</strong></p>
  
  <pre><code>class Item &lt; ActiveRecord::Base
    attr_accessible :name, :sku, :item_type, :comments, :item_variants_attributes
  
  
    # Associations
    #-----------------------------------------------------------------------
    belongs_to :company
    belongs_to :item_type
    has_many   :item_variants
  
    accepts_nested_attributes_for :item_variants, allow_destroy: true
  
  end
  </code></pre>
  
  <p><strong>item_variant.rb</strong></p>
  
  <pre><code>class ItemVariant &lt; ActiveRecord::Base
    attr_accessible :item_id, :location_id
  
    # Associations
    #-----------------------------------------------------------------------
    belongs_to :item
  
  end
  </code></pre>
  
  <p><strong>item/new.html.erb</strong></p>
  
  <pre><code>&lt;%= form_for [@company, @item] do |f| %&gt;
    ...
    ...
    &lt;%= f.fields_for :item_variants do |builder| %&gt;
      &lt;fieldset&gt;
        &lt;%= builder.label :location_id %&gt;
        &lt;%= builder.collection_select :location_id, @company.locations.order(:name), :id, :name, :include_blank =&gt; true %&gt;
      &lt;/fieldset&gt;
    &lt;% end %&gt;
    ...
    ...
  &lt;% end %&gt;
  </code></pre>