ReflectionException is thrown when mapping entitie

I'm trying to use Doctrine 2 in a ZF2 application which contains two modules, each with its own database. I need to use cross-database joins so that I can associate entities from one module with entities in another. Here's a UML diagram of the setup.

I've tried using this in my first entity (I've removed irrelevant parameters and use statements):

namespace Client\Entity;

/**
 * A website.
 *
 * @ORM\Entity
 * @ORM\Table(name="users.website")
 * ...
 * @property $server
 */
class Website extends BaseEntity {

    // Other class vars ... 

    /**
     * @ORM\ManyToOne(targetEntity="Server\Entity\Server", inversedBy="websites")
     * @ORM\JoinColumn(name="server_id", referencedColumnName="id")
     */
    protected $server;

And this in my server entity:

namespace Server\Entity;

/**
 * A server.
 *
 * @ORM\Entity
 * @ORM\Table(name="servers.server")
 * ...
 * @property $websites
 */
class Server extends BaseEntity {

   // Other class vars ... 

   /**
    * @ORM\OneToMany(targetEntity="Client\Entity\Website", mappedBy="server")
    */
   protected $websites;

This mapping works perfectly when I create a new website entity (via a web form which uses DoctrineModule\Form\Element\ObjectSelect for the server association), but when I go to edit an existing website, this ReflectionException is thrown:

Class Server\Entity\Website does not exist

The full stack trace can be found here. For some reason, when the Server entity is accessed from its association with a Website entity, it thinks all of the entities exist in the Server\Entity namespace rather than Client\Entity. What do I need to do to make sure the Server entity looks in the correct module namespace?

The CLI command orm:info produces:

Found 7 mapped entities:
[OK]   Server\Entity\Server
[OK]   Client\Entity\Role
[OK]   Client\Entity\Website
[OK]   Client\Entity\User
[OK]   Client\Entity\Client
[OK]   Client\Entity\Permission
[OK]   Message\Entity\Notification

But orm:validate-schema results in:

[Mapping]  OK - The mapping files are correct.
[Database] FAIL - The database schema is not in sync with the current mapping file.

I have this in each one of my module's module.config.php:

'driver' => array(
    __NAMESPACE__ . '_driver' => array(
        'class' => 'Doctrine\ORM\Mapping\Driver\AnnotationDriver',
        'cache' => 'array',
        'paths' => array(__DIR__ . '/../src/' . __NAMESPACE__ . '/Entity')
    ),
    'orm_default' => array(
        'drivers' => array(
            __NAMESPACE__ . '\Entity' => __NAMESPACE__ . '_driver'
        )
    )
)

I managed to fix it. In my Server\Entity\Server, I had these getter/setter functions for adding/removing websites:

public function setWebsite(Website $website) 
{
   $this->websites->add($website);    
}

public function removeWebsite(Website $website)
{
   $this->websites->removeElement($website);
}

But you need to specify the full namespace as the argument:

public function setWebsite(\Client\Entity\Website $website) { ... }

Such a stupid mistake! I found the issue because I trawled through every file in the stack-trace and got to the point where it was attempting to save every method/argument in my Entity class to a proxy file (line 223ish in Doctrine/ORM/Proxy/ProxyFactory.php).