Error: undefined table, when trying to access PostgreSQL with Doctrine2

I want to access a PostgreSQL Database with Doctrine 2 in a Zend 2 Application, but I get the error, that the table I want to access is not defined.

The same access on a MySQL Database works fine.

My Doctrine configuration (local.php) is:

return array(
 'doctrine' => array(
    'connection' => array(
        'orm_default' => array(
            // MySQL - Config
//                 'driverClass' => 'Doctrine\DBAL\Driver\PDOMySql\Driver',
//                 'params' => array(
//                     'host'     => '192.168.1.100',
//                     'port'     => '3306',
//                     'user'     => 'user',
//                     'password' => 'password',
//                     'dbname'   => 'mydb',
//                     'charset'  => 'utf8',
//                 ),
            // PostgreSQL
            'driverClass' => 'Doctrine\DBAL\Driver\PDOPgSql\Driver',
            'params' => array(
                    'host'     => '192.168.1.100',
                    'port'     => '5432',
                    'user'     => 'user',
                    'password' => 'password',
                    'dbname'   => 'mydb',
                    'charset'  => 'utf8',
            ),
        ),
    ),
  ),
);

My Controller tries to display an Entity "Horse":

class HorsesController extends AbstractActionController
{

  /**
   * @var Doctrine\ORM\EntityManager
   */
  protected $em;

  public function getEntityManager()
  {
    if (null === $this->em) {
        $this->em = $this->getServiceLocator()->get('doctrine.entitymanager.orm_default');
    }
    return $this->em;
  }

  /**
   * The default action - show the home page
   */
  public function indexAction()
  {
    $id = (int)$this->getEvent()->getRouteMatch()->getParam('id');
    $horse = $this->getEntityManager()->find('Doctrine2mapper\Entity\Horse', $id);
    return new ViewModel(array(
            'horse' => $horse,
    ));
  }
}

The Entity Horse is:

use Doctrine\ORM\Mapping as ORM;
use Doctrine\Common\Collections\ArrayCollection;
use Doctrine\Common\Collections\Collection;

use Zend\Form\Annotation; // !!!! Absolutely neccessary

use Zend\Db\Sql\Ddl\Column\BigInteger;

/**
 * Horses
 *
 * @ORM\Table(name="Horse")
 * @ORM\Entity(repositoryClass="Doctrine2mapper\Entity\Repository\HorseRepository")
 * @Annotation\Name("Horse")
 * @Annotation\Hydrator("Zend\Stdlib\Hydrator\ClassMethods")
 */
class Horse
{

    /**
     * @var integer
     *
     * @ORM\Column(name="id", type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="IDENTITY")
     * @Annotation\Exclude()
     */
    private $id;

    /**
     * Get id
     *
     * @return integer 
     */
    public function getId()
    {
        return $this->id;
    }
.
.
.
(many attributes, getter and setter)

When trying to access PostgreSQL I get this error:

An exception occurred while executing 'SELECT t0.id AS id1, ...
FROM Horse t0 WHERE t0.id = ?' with params [1]:

SQLSTATE[42P01]: Undefined table: 7 ERROR:  relation "horse" does not exist
LINE 1: ...ated AS created29, t0.modified AS modified30 FROM Horse t0 W...

I have a PostgreSQL Database "mydb" with the schema "public" and the table "Horse"

-- Table: "Horse"

CREATE TABLE "Horse"
(
  id serial NOT NULL,
  .
  .
  . 
);

exists and can be accessed using pgAdminIII.

Any help is welcome!

Best regards rholtermann