title: Symfony2 PUGXMultiUserBundle : registration doesn't work
body: <p>I am trying to use PUGXMultiUserBundle in my application ; I followed the instructions in documentation, but when I go on the registration page, I got an error :</p>
  
  <blockquote>
    <p>Impossible to set the class discriminator, because the class "Myapp\UserBundle\Entity\SellerUser" is not present in the entities list </p>
  </blockquote>
  
  <p>I think that everything is well configured, but I can't see where the bug is. </p>