title: Doctrine doesn't find a column when updating the schema
body: <p>When I try to update my schemas, I got this message</p>
  
  <pre><code>[@localhost you]$ php app/console doctrine:schema:update --force
  
    [Doctrine\DBAL\Schema\SchemaException]                                      
    There is no column with name 'family_id' on table 'unit__family__convert'.  
  </code></pre>
  
  <p>This is the beginning of my class UnitFamilyConvert</p>
  
  <pre><code>/**
   * UnitFamilyConvert
   *
   * @ORM\Table(name="unit__family__convert")
   * @ORM\Entity()
   * @ExclusionPolicy("all")
   */
  class UnitFamilyConvert
  {
    /**
     * @var integer
     *
     * @ORM\Column(name="family_id", type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     * @Expose
     * @Groups({"All"})
     */
      private $family_id;
  </code></pre>
  
  <p>I already tried to clean the ORM's cache with</p>
  
  <pre><code>app/console doctrine:cache:clear-metadata 
  app/console doctrine:cache:clear-query
  app/console doctrine:cache:clear-result app/console cache:clear
  </code></pre>
  
  <p>Why Doctrine cannot find my column ?</p>