Undefined method "errors"... But there are ERRORS

I am doing a basic validation for a bank entry and am trying to display the errors on submit. Here is my validation and html.

class GuestbookEntry < ActiveRecord::Base
  validates :body, presence: :true
end

This is my html:

<% form_for @guestbook_entry do |f| %>                                                                                   
  <% if @guestbook_entry.errors.any? %>                                                                                
    <% @guestbook_entry.errors.full_messages.each do |m| %>                                                                                         
      <li><%= m %></li>                                                                                          
    <% end %>                                                                                                   
  <% end %>                                                                                 
  <%= f.label :body, "Guestbook Entry:" %>                                                                                     
  <%= f.text_area :body %>                                                                                                         
  <%= f.submit "Submit" %>                                                                                     
<% end %>

Any ideas?