[zend] ManyToMany probleem

Ik heb het volgende probleem
No reference from table Application_Model_DbTable_Task to table Application_Model_DbTable_Tasksuser

Nu heb ik het volgende in mijn controller
<?php
$user = new Application_Model_DbTable_Users();
//de 5 is de id van de user
$us = $user->find(5);
$userGegevens = $us->current();

$manyTomany = $userGegevens->findManyToManyRowset(
'Application_Model_DbTable_Tasksuser',
'Application_Model_DbTable_Task'
)->toArray();
var_dump($manyTomany);
?>

Nu de models:
<?php
class Application_Model_DbTable_Users extends Zend_Db_Table_Abstract
{

protected $_name = 'users';
protected $_primary = 'id';


protected $_dependentTables = array(
'Application_Model_DbTable_Tasksusers'
);
}


/*
*
*/
class Application_Model_DbTable_Tasksuser extends Zend_Db_Table_Abstract
{
protected $_name = 'tasks_users';
//protected $_dependentTables = array('Application_Model_DbTable_Task');

protected $_referenceMap = array(
'users' => array(
'Columns' => array('user_id'),
'refColumns' => array('id'),
'refTableClass' => 'Application_Model_DbTable_Users',
),

'tasks' => array(
'Columns' => array('task_id'),
'refColumns' => array('id'),
'refTableClass' => 'Application_Model_DbTable_Task',
)

);
}

class Application_Model_DbTable_Task extends Zend_Db_Table_Abstract
{

protected $_name = 'tasks';
protected $_primary = 'id';

protected $_dependentTables = array(
'Application_Model_DbTable_Tasksusers'
);
}
?>


Wie ziet hier het probleem?