corcel: Undefined property: Corcel\Post::$meta

Hi!! I am trying to install the package but I get this error:

Undefined property: Corcel\Post::$meta
********
public function __get($key)
    {
        if (!isset($this->$key)) {
          -->ERROR IS HERE?  return $this->meta->$key;    
        }
********

Can you guide me where can be the error?

I have this code:

$params = array(
            'database'  => 'syscover-wp',
            'username'  => 'carlos',
            'password'  => '33527667Sb',
        );
        \Corcel\Database::connect($this->params);
        $post = Post::published()->get();

thanks!!