title: uninitialized constant CustomerBill::CustomerBillLineItem
body: <p>I created an association between <code>customer_bill</code> and <code>customer_bill_line_item</code> as follows:</p>
  
  <pre><code>class CustomerBill &lt; ActiveRecord::Base
    attr_accessible :customer_bill_line_items_attributes
    has_many :customer_bill_line_items, :dependent =&gt;:destroy
  
    accepts_nested_attributes_for :customer_bill_line_items, :allow_destroy =&gt; true
  end
  
  class CustomerBillLineItem &lt; ActiveRecord::Base
    attr_accessible :customer_bill_id 
    belongs_to :customer_bill, :foreign_key =&gt; "customer_bill_id"
  end
  </code></pre>
  
  <p>When I enter a form in create mode, I get the following error:</p>
  
  <pre><code>uninitialized constant CustomerBill::CustomerBillLineItem
  
  Extracted source (around line #66):
  
  63:                             &lt;%end%&gt;
  64:                            
  65:                            
  66:             &lt;%= f.fields_for :customer_bill_line_items do |builder| %&gt;
  67:             &lt;%= render 'customer_bill_line_item_fields', :f =&gt; builder %&gt;
  68:             &lt;%end%&gt;
  </code></pre>
  
  <p>The full stack trace is given in the comment.</p>
  
  <p>Is there an association that must be made in <code>customer_bills_controller</code> like<code>@customer_bill.customer_bill_line_items</code>??</p>
  
  <p>Guidance required. Thanks in advance.</p>