Symfony2 security login issue

Question

I want to implement simple login/logout and registration procedure using symfony2 i start by reading tutorial and using symfony demo application but i can't get rid of this error from my log:

[2015-09-11 07:14:37] security.INFO: Authentication request failed. {"exception":"[object] (Symfony\Component\Security\Core\Exception\BadCredentialsException(code: 0): Bad credentials. at /home/saeed/ESN0.1/ESN0.1.0/vendor/symfony/symfony/src/Symfony/Component/Security/Core/Authentication/Provider/UserAuthenticationProvider.php:90, Symfony\Component\Security\Core\Exception\BadCredentialsException(code: 0): The presented password is invalid. at /home/saeed/ESN0.1/ESN0.1.0/vendor/symfony/symfony/src/Symfony/Component/Security/Core/Authentication/Provider/DaoAuthenticationProvider.php:67)"} []

so it stays on the login page. this is my security.yml:

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

providers:
    database_users:
        entity: { class: AppBundle:User, property: username }
firewalls:
    secured_area:
        pattern: ^/
        anonymous: true
        form_login:
            check_path: security_login_check
            login_path: security_login_form
        logout:
            path: security_logout
            target: security_login_form

access_control:
    - { path: ^/admin, roles: ROLE_ADMIN }

This is the login template div:

<div id="login-form">
                        <form action="{{ path('security_login_check') }}" method="post">
                            <fieldset>
                                <div class="form-row">
                                    <input type="text" id="username" name="_username"  class="form-input" onfocus="this.placeholder = ''"  onblur="this.placeholder='نام کاربری'"   placeholder="نام کاربری" />
                                </div>
                                <div class="form-row">
                                    <input type="password" id="password" name="_password"  class="form-input" onfocus="this.placeholder = ''" onblur="this.placeholder = 'رمز عبور'"    placeholder="رمز عبور"/>
                                </div>
                                    <button id="login-btn" type="submit">ورود</button>
                            </fieldset>
                        </form>
                    </div>

and the controllers:

/**
     * @Route("/login", name="security_login_form")
     */
    public function loginAction()
    {
//        $user = $this->get('security.token_storage')->getToken()->getUser();
        if($this->container->get('security.authorization_checker')->isGranted('IS_AUTHENTICATED_FULLY'))
           return $this->redirectToRoute('dashboard');
        $helper = $this->get('security.authentication_utils');
        $isLogin  = true;
        return $this->render('::login-Register.html.twig', array(
                // last username entered by the user (if any)
                'last_username' => $helper->getLastUsername(),
                // last authentication error (if any)
//                'error' => $helper->getLastAuthenticationError(),
                'isLogin' => $isLogin,
            ));
    }


    /**
     * This is the route the login form submits to.
     *
     * But, this will never be executed. Symfony will intercept this first
     * and handle the login automatically. See form_login in app/config/security.yml
     *
     * @Route("/login_check", name="security_login_check")
     */
    public function loginCheckAction()
    {
        throw new \Exception('This should never be reached!');
    }

Registration controller

/**
     *
     * @Route("/register",name="register_user")
     */
    public function registerAction(Request $request){
        if($request->isMethod("POST")){
            $userRepo = $this->getDoctrine()->getRepository('AppBundle:User');
            $tempUser = $userRepo->find('AppBundle:User' , $request->get("username"));
            try{
                if(empty($tempUser)){
                    $plainPassword = $request->get("password");
                    $user = $userRepo->getUserByRequest($request);
                    $encoder = $this->container->get('security.password_encoder');
                    $encoded = $encoder->encodePassword($user, $plainPassword);
                    $user->setPassword($encoded);
                    $userRepo->saveUser($user);

                    $token = new UsernamePasswordToken($user, null, 'main', $user->getRoles());
                    $this->get('security.token_storage')->setToken($token);
                    return $this->redirectToRoute('dashboard');
                }else{
                    throw new Exception('user already exist');
                }
            }catch (AuthenticationException $e){

                return $this->render(
                    'login-Register.html.twig'
                );
            }
        }else{
            $isLogin = 2;
            return $this->render('::login-Register.html.twig',
                array(
                    'isLogin' => $isLogin,
                ));
        }
    }

finally the user entity fileds:

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

    /**
     * @var string
     *
     * @ORM\Column(name="username", type="string", length=100,nullable=false,unique=true)
     */
    private $username;

    /**
     * @var string
     *
     * @ORM\Column(name="password", type="string", length=255,nullable=false)
     */
    private $password;

    /**
     * @var string
     *
     * @ORM\Column(name="email", type="string", length=100,nullable=false,unique=true)
     */
    private $email;

    /**
     * @var string
     *
     * @ORM\Column(name="name", type="string", length=100)
     */
    private $name;

i increase the length of password field to 255 but that does'nt solve my problem either.