"403: access denied" when using a new privilege

Hi.

As part of my attempt to create an Items duplicating plugin (Duplicate an Item), I’ve tried to extend the privileges for the Contributor role, like this

public function hookDefineAcl($args)
    {
        $acl = $args['acl'];
        // contributors are able to duplicate
		$acl->allow('contributor', 'Items', 'duplicate');
    }

then adding duplicateAction() functions in both ItemsController.php and AbstractActionController.php files.

It all works fine when I’m logged in as Admin, but when I log in as Contributor I get a 403: Access Denied message everytime I click on my “Duplicate” link.

What am I missing? Anybody could point me in the right direction?

Thanks.

Found the cause: I had mistyped

protected $_hooks = array('define_acl');

writing defineacl instead of the correct name.
Now everything works fine.