preUpload() does not exist, or could not be auto-loaded.

je trouve ce probléme au cours de création schema

[Doctrine\Common\Annotations\AnnotationException]
[Semantical Error] The annotation "@Doctrine\ORM\Mapping\PrepPersist" in method ventenligneBundle\Entity\Media::preUpload() does not
exist, or could not be auto-loaded.

code entity Media:

        <?php

namespace ventenligneBundle\Entity;

use Doctrine\ORM\Mapping as ORM;
use Symfony\Component\validator\Constraints as Assert;

/**
 * Media
 *
 * @ORM\Table()
 * @ORM\Entity(repositoryClass="ventenligneBundle\Entity\MediaRepository")
 * @ORM\HasLifecycleCallbacks
 */
class Media
{
    /**
     * @var integer
     *
     * @ORM\Column(name="id", type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    private $id;

     /**
     * @var \DateTime
     *
     * @ORM\COlumn(name="updated_at",type="datetime", nullable=true)
     */
    private $updateAt;

    /**
     * @ORM\PostLoad()
     */
    public function postLoad()
    {
        $this->updateAt = new \DateTime();
    }

    /**
     * @ORM\Column(type="string",length=255)
     */
    public $name;

    /**
     * @ORM\Column(type="string",length=255, nullable=true)
     */
    public $path;

    public $file;

      public function getUploadRootDir()
    {
        return __dir__.'/../../../web/uploads/produit';
    }

    public function getAbsolutePath()
    {
        return null === $this->path ? null : $this->getUploadRootDir().'/'.$this->path;
    }

    public function getAssetPath()
    {
        return 'uploads/'.$this->path;
    }

    /**
     * @ORM\PrepPersist()
     * @ORM\PreUpdate()
     */
    public function preUpload()
    {
        $this->tempFile = $this->getAbsolutePath();
        $this->oldFile = $this->getPath();
        $this->updateAt = new \DateTime();

        if (null !== $this->file)
            $this->path = sha1(uniqid(mt_rand(),true)).'.'.$this->file->guessExtension();
    }

    /**
     * @ORM\PostPersist()
     * @ORM\PostUpdate()
     */
    public function upload()
    {
        if (null !== $this->file) {
            $this->file->move($this->getUploadRootDir(),$this->path);
            unset($this->file);

            if ($this->oldFile != null) unlink($this->tempFile);
        }
    }

    /**
     * @ORM\PreRemove()
     */
    public function preRemoveUpload()
    {
        $this->tempFile = $this->getAbsolutePath();
    }

    /**
     * @ORM\PostRemove()
     */
    public function removeUpload()
    {
        if (file_exists($this->tempFile)) unlink($this->tempFile);
    }

    /**
     * Get id
     *
     * @return integer
     */
    public function getId()
    {
        return $this->id;
    }

    public function setPath($path)
    {
        $this->path = $path;

        return $this;
    }

    /**
     * Get path
     *
     * @return string
     */
    public function getPath()
    {
        return $this->path;
    }

    /**
     * Get name
     *
     * @return \string
     */

     public function getName()
    {
        return $this->name;
    }

    /**
     * Set updateAt
     *
     * @param \DateTime $updateAt
     * @return Media
     */
    public function setUpdateAt($updateAt)
    {
        $this->updateAt = $updateAt;

        return $this;
    }

    /**
     * Get updateAt
     *
     * @return \DateTime
     */
    public function getUpdateAt()
    {
        return $this->updateAt;
    }

    /**
     * Set name
     *
     * @param string $name
     * @return Media
     */
    public function setName($name)
    {
        $this->name = $name;

        return $this;
    }

}

quelle est la solution et merci d'avance