Get HELPER from Resources

[Roka]

Hi guys,
I need a little help...
So i develop a custom add-on who read content from resource_forum_list_sidebar .
I do well, but i can't get the prefixes.

In Listener.php add this:

    public static function dependencies(XenForo_Dependencies_Abstract $dependencies, array $data)
    {
        XenForo_Template_Helper_Core::$helperCallbacks['resourceprefix'] = array('XenResource_ViewPublic_Helper_Resource', 'getResourcePrefixTitle');

    }

In template use

{xen:helper resourcePrefix, $resource}

But nothing happens.

Can i make a custom Helper to read just prefixes (without link to prefix group) just show prefix (without any link)?
Same as Top Resources sidebar.

Regards,