title: undefined method `error_messages_for' for #<#<Class:0x3981390>:0x
body: <p>problem like this:</p>
  
  <blockquote>
    <p>undefined method `error_messages_for' for #&lt;#:0x3a4f700></p>
  </blockquote>
  
  <p>My English is very rubbish, who can help me solve the problem? thanks</p>