VichUploaderBundle, field null image_name

I've been trying for days to integrate VichUploaderBundle into a symfony 3.4 project with mySql. I followed the documentation of link but I have a problem that I could not solve.

The error occurs in the flush () when creating a new record.

  

SQLSTATE [23000]: Integrity constraint violation: 1048 Column 'image_name' can not be null

It does not assign any value to the fields imageName, imageSize, updatedAt.

  

An exception occurred while executing 'INSERT INTO box (date, user, amount, type, cajaconcepto_id, moneda_id, nula, obs, hab, doc, pax, time, image_name, image_size, updated_at) VALUES (?,?,? ,?,?,?,?,?,?,?,?,?,?,?,?,?) 'with params ["2018-03-30", {}, 2, "2", {}, { }, 0, "2", null, null, null, "19:13:56", null, null, null]:

My code is as follows:

/app/config/config.yml

vich_uploader:
db_driver: orm # or mongodb or propel or phpcr

mappings:
    product_image:
        uri_prefix: /pdf/adjuntos
        upload_destination: '%kernel.project_dir%/public/pdf/adjuntos

/src/CajaBundle/Entity/Caja.php     ...     ...

/**
 * NOTE: This is not a mapped field of entity metadata, just a simple property.
 * 
 * @Vich\UploadableField(mapping="product_image", fileNameProperty="imageName", size="imageSize")
 * 
 * @var File
 */
private $imageFile;

/**
 * @ORM\Column(type="string", length=255)
 *
 * @var string
 */
private $imageName;

/**
 * @ORM\Column(type="integer")
 *
 * @var integer
 */
private $imageSize;

/**
 * @ORM\Column(type="datetime")
 *
 * @var \DateTime
 */
private $updatedAt;

/**
 * If manually uploading a file (i.e. not using Symfony Form) ensure an instance
 * of 'UploadedFile' is injected into this setter to trigger the  update. If this
 * bundle's configuration parameter 'inject_on_load' is set to 'true' this setter
 * must be able to accept an instance of 'File' as the bundle will inject one here
 * during Doctrine hydration.
 *
 * @param File|\Symfony\Component\HttpFoundation\File\UploadedFile $image
 */
public function setImageFile(?File $image = null): void
{
    $this->imageFile = $image;

    if (null !== $image) {
        // It is required that at least one field changes if you are using doctrine
        // otherwise the event listeners won't be called and the file is lost
        $this->updatedAt = new \DateTimeImmutable();
    }
}

public function getImageFile(): ?File
{
    return $this->imageFile;
}

public function setImageName(?string $imageName): void
{
    $this->imageName = $imageName;
}

public function getImageName(): ?string
{
    return $this->imageName;
}

public function setImageSize(?int $imageSize): void
{
    $this->imageSize = $imageSize;
}

public function getImageSize(): ?int
{
    return $this->imageSize;
}
...
...

/src/CajaBundle/Controller/DefaultController.php

...
...
$form = $this->createFormBuilder($caja)
->add('imageFile', VichImageType::class, [
'required' => false,
'allow_delete' => true,
'download_label' => '...',
'download_uri' => true,
'download_label' => 'download_file',
'image_uri' => true,
'imagine_pattern' => '...',
])
...
...

/src/CajaBundle/Resources/views/Default/egreso.html.twig

...
...
<div class="form-group"> 
  <label>Adjunto:</label>
  {{ form_errors(form.imageFile) }}
  {{ form_widget(form.imageFile, {'required': false}) }}  
</div>   
...
...

Any orientation will be welcome. Thanks in advance