[fw-general] Zend_Acl::add() may not accept extended classes

[J DeBord]

I'm experimenting with Zend_Acl and even though what I am doing may not be
the best way to go about hiding/displaying navigation, the error message
below does not appear to be correct:*

Catchable fatal error*: Argument 1 passed to Zend_Acl::add() must implement
interface Zend_Acl_Resource_Interface, instance of
Zend_View_Helper_Navigation given

As you can see, Zend_View_Helper_Navigation does indeed implement
Zend_Acl_Resource_Interface

What do you guys think?

<?php

class Zend_View_Helper_Navigation extends Zend_View_Helper_Abstract
implements Zend_Acl_Resource_Interface {

    protected $resourceId = 'navigation';

    public function navigation() {

        return $this->view->partial('navigation.phtml', array());

    }

    /**
     * (non-PHPdoc)
     * @see
library/Zend/Acl/Resource/Zend_Acl_Resource_Interface#getResourceId()
     */
    public function getResourceId() {
        return $this->_resourceId;
    }

}