Unable to load extension annonation using Laravel 5.5, Laravel-Doctrine 1.4.2

[kunxin-chor]

Hi I am trying to use the Timestamp extension, however when I attempt update the schema I get the following:

[Semantical Error] The annotation "@Gedmo\Mapping\Annotation\Timestampable" in property
   App\Contacts\Domain\Contact\Contact::$created_at does not exist, or could not be auto-
  loaded.

Here's the property in question:

/**
     * @Gedmo\Timestampable(on="create")
     * @ORM\Column(type="datetime", nullable=true)
     */
    protected $created_at;

I have tried:

1. Including the GedmoExtensionServiceProvider
2. Including the DoctrineServiceProvider after the former (and the other way round)
3. Flushing my config cache