title: How to define/pass the entity manager for sonata-admin
body: <p>I followed <a href="http://symfony2.ylly.fr/sonataadminbundle-fosuserbundle-have-a-good-base-project-jordscream/" rel="nofollow">this tutorial</a> to install SonataAdmin with FOSUserBundle.</p>
  
  <p>Now i keep getting this Error Message:
  No entity manager defined for class Application\Sonata\UserBundle\Entity\User</p>
  
  <p>But how do i set/pass the EntityManager?
  I haven't found anything about configuring it or any hint on what this error means.
  Any help anyone?</p>
  
  <hr>
  
  <p><strong>Edit #1:</strong></p>
  
  <p>As asked for, here is what i have in my config.yml for sonata so far:</p>
  
  <pre><code>sonata_block:
      default_contexts: [cms]
      blocks:
          sonata.admin.block.admin_list:
              contexts:   [admin]
          sonata.block.service.text:
          sonata.block.service.rss:
  </code></pre>
  
  <hr>
  
  <p><strong>Edit #2:</strong></p>
  
  <p>I added the entity manager configuration part for Doctrine2 ORM Admin thou it is mentioned in the Documentation that if left null, it should just use the default. Still, it doesn't solve my problem.</p>
  
  <pre><code>sonata_doctrine_orm_admin:
      # default value is null, so doctrine uses the value defined in the configuration
      entity_manager: '@doctrine.orm.entity_manager'
  </code></pre>
  
  <hr>
  
  <p><strong>Edit #3:</strong>
  I did set auto_mapping to true as well, even thou that also is true by default.
  Still no Solution to this Problem.</p>