Taxonomy doesn't exist

I’ve created custom taxonomy with Types plugin (Currently deactivated).
In my DDBB I can see in ‘wp_term_taxonomy’ a good list of entries with terms and this category ‘mytaxonomy’ associated to them.
If I try to check if the category exists with taxonomy_exists() it saids it doesn’t, if I search for empty ones:

$taxonomy = 'mytaxonomy';
$term_args=array(
  'hide_empty' => false,
  'orderby' => 'name',
  'order' => 'ASC'
);
$tax_terms = get_terms($taxonomy,$term_args);
if(is_wp_error($tax_terms))
{
  echo $tax_terms->get_error_message().'<br />';
}
else
{
  echo 'No error';
}

It doesn’t exists neither. If I search for custom ones, not built in:

$args = array(
  'public'   => true,
  '_builtin' => false

);
$output = 'names'; // or objects
$operator = 'and'; // 'and' or 'or'
$taxonomies = get_taxonomies( $args, $output, $operator );
if ( $taxonomies ) {
  foreach ( $taxonomies  as $taxonomy ) {
    echo '<p>' . $taxonomy . '</p>';
  }
}

It doesn’t appear…
What is exactly what I can see in the DDBB?
A delusion????
A need a break now, can somebody, please, explain me this?