error_messages_for错误怎么解决？

<div class="depot-form">
 
 <%= error_messages_for 'order' %>
 
 <fieldset>
  <legend>lease Enter Your Details</legend>

  <% form_for rder, :url => { :action => :save_order } do |form| %>
  <p>
   <label for="order_name">Name:</label>
   <%= form.text_field :name, :size => 40 %>
  </p>

  <p>
   <label for="order_address">Address:</label>
   <%= form.text_area :address, :rows => 3, :cols => 40 %>
  </p>

  <p>
   <label for="order_email">E-Mail:</label>
   <%= form.text_field :email, :size => 40 %>
  </p>

  <p>
   <label for="order_pay_type">ay with:</label>
   <%=
    form.select :pay_type,
        Order:AYMENT_TYPES,
        :prompt => "Select a payment method"
   %>
  </p>
 
  <%= submit_tag "lace Order", :class => "submit" %>
  <% end %> 
 </fieldset>
</div>
说是没有定义errors，