Asset Collection!

Hey,

I am trying to use Css an Js asset collection in the ControllerBase initialize function. So far everything is fine, but when I try to use the collection in the .volt file I always get the error that the collection is not known in the manager.

Here the code: ControllerBase.php

class ControllerBase extends \Phalcon\Mvc\Controller
{
    /**
     * Execute before the router so we can determine if this is a private controller, and must be authenticated, or a
     * public controller that is open to all.
     *
     * @param Dispatcher $dispatcher
     * @return boolean
     */
    public function initialize()
    {
        $this->assets
             ->collection('cssStyle')
             ->addCss('third-partyassets/plugins/fullcalendar/fullcalendar.css', false, false)
             ->addCss('third-party/assets/plugins/assets/css/custom-icon-set.css', false, false)
             ->addCss('assets/css/custom-icon-set.css', false, false)
             ->addCss('css/style.css')
             ->setTargetPath('css/production.css')
             ->setTargetUri('css/production.css')
             ->addFilter(new \Phalcon\Assets\Filters\Cssmin());
    }

.volt File

{{ this.assets.outputCss('cssStyle') }}

When I try to use the following code in the index.php the collection gets recognized. Where is my error??????

$di['assets']
            ->collection('cssStyle')
            ->addCss('stylesheets/vendor/reseter.css')
            ->addCss('stylesheets/vendor/reseter1.css')
            ->addCss('stylesheets/application.css');