Symfony:从数据库加载安全用户

我阅读了Symfony的官方文档，以便访问特定的页面。我按照说明做了，但是当我插入user和pw时，我没有被重定向到受保护的页面。

这是实体

namespace AppBundle'Entity;
use Symfony'Component'Security'Core'User'UserInterface;
use Symfony'Component'Security'Core'User'AdvancedUserInterface;
use Doctrine'ORM'Mapping as ORM;
/**
* @ORM'Entity
* @ORM'Table(name="users")
*/
class User implements UserInterface, 'Serializable
{
/**
 * @ORM'Column(type="integer")
 * @ORM'Id
 * @ORM'GeneratedValue(strategy="AUTO")
 */
private $id;
/**
 * @ORM'Column(type="string", length=25, unique=true)
 */
private $username;
/**
 * @ORM'Column(type="string", length=64)
 */
private $password;
/**
 * @ORM'Column(type="string", length=60, unique=true)
 */
private $email;
/**
 * @ORM'Column(name="is_active", type="boolean")
 */
private $isActive;
public function __construct()
{
    $this->isActive = true;
    // may not be needed, see section on salt below
    // $this->salt = md5(uniqid(null, true));
}
public function getUsername()
{
    return $this->username;
}
public function getSalt()
{
    // you *may* need a real salt depending on your encoder
    // see section on salt below
    return null;
}
public function getPassword()
{
    return $this->password;
}
public function getRoles()
{
    return array('ROLE_ADMIN');
}
public function eraseCredentials()
{
}
/** @see 'Serializable::serialize() */
public function serialize()
{
    return serialize(array(
        $this->id,
        $this->username,
        $this->password,
        // see section on salt below
        // $this->salt,
    ));
}
/** @see 'Serializable::unserialize() */
public function unserialize($serialized)
{
    list (
        $this->id,
        $this->username,
        $this->password,
        // see section on salt below
        // $this->salt
    ) = unserialize($serialized);
   }

这是security.yml

security:
encoders:
    AppBundle'Entity'User:
        algorithm: bcrypt

role_hierarchy:
    ROLE_ADMIN:       ROLE_ADMIN
    ROLE_SUPER_ADMIN: [ ROLE_ADMIN, ROLE_ALLOWED_TO_SWITCH ]
providers:
    our_db_provider:
        entity:
            class: AppBundle:User
            property: username
firewalls:
    dev:
        pattern: ^/(_(profiler|wdt|error)|css|images|js)/
        security: false
    main:
        anonymous: ~
        http_basic: ~
    default:
       pattern:    ^/
       http_basic: ~
       provider: our_db_provider
access_control:
    - { path: ^/dashboard/admin, roles: ROLE_ADMIN }

密码已使用BCrypt工具手动插入数据库

我做错了什么?