symfony validation constraint ClassNotFoundException

My custom constraint class is not found and I don't know where is the problem.
this is the error

Attempted to load class "CompanyTransferConstraint" from namespace "FM\FMBundle\Validator\Constraints". Did you forget a "use" statement for another namespace? 500 Internal Server Error - ClassNotFoundException

the constraint class and the validator class are both located in src/FM\FMBundle\Validator\Constraints

here is my code :
CompanyTransferConstraint

<?php

namespace FM\FMBundle\Validator\Constraints;

use Symfony\Component\Validator\Constraint;

/**
 * @Annotation
 */

class CompanyTransferConstraint extends Constraint
{
    public $message = 'You do not have the requested amount';
    public function validatedBy()
    {
        return get_class($this).'Validator';
    }
}

CompanyTransferConstraintValidator

<?php
namespace FM\FMBundle\Validator\Constraints;

use Symfony\Component\Validator\Constraint;
use Symfony\Component\Validator\ConstraintValidator;

class CompanyTransferConstraintValidator extends ConstraintValidator
{
    public function validate($value, Constraint $constraint)
        {

            if ($value>200) {
                $this->context->buildViolation($constraint->message)
                    ->addViolation();
            }
        }
}

the Form Type

<?php

namespace FM\FmBundle\Form\Type\Dash;

use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\Validator\Constraints\NotBlank;
use FM\FMBundle\Validator\Constraints\CompanyTransferConstraint;
use Symfony\Component\Validator\Constraints\Type;

class CompanyTransferType extends AbstractType
{
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder
            ->add('totalAmount','integer',
                    array(
                        'constraints' => 
                            array(
                                new NotBlank(),
                                new Type('integer'),
                                new CompanyTransferConstraint(),
                            )
                    )

            )
            ->add('save','submit')
        ;
    }
    public function getName()
    {
        return 'fm_fmbundle_company_transfer';
    }
}

I also tested it with a User entity like this

/*
...
*/
use FM\FMBundle\Validator\Constraints as FmAssert;
class User extends BaseUser 
{
  /*
     .....
  */
    /**
     * @FmAssert\CompanyTransferConstraint
     */
    protected $phone;

  /*
     .....
  */
}

and I get this error

AnnotationException in AnnotationException.php line 54: [Semantical Error] The annotation "@FM\FMBundle\Validator\Constraints\CompanyTransferConstraint" in property FM\FmBundle\Entity\User::$phone does not exist, or could not be auto-loaded.