Empty response from Zend_Amf_Server

When I call endpoint from flash all the action is done well but the response is empty. The code is:

class AmfController extends Zend_Controller_Action {
    public function indexAction()
    {
        $server = new Zend_Amf_Server();
        $server->setProduction(false);
        $server->setClass('Application_Model_Amf');
        $response = $server->handle();
        echo $response;
    }
}

and

class Application_Model_Amf {
    /**
     *
     * @param bytearray $data
     * @param string $dateString
     * @return int
     */
    public function save($data, $dateString)
    {
        $dateString = str_replace(array('|', ':'), array('_', ''), $dateString);
        //file_put_contents("$dateString.jpg", $data);
        $r = new stdClass();
        $r->error = 0;
        return $r;
    }
}

I also tried

    public function save($data, $dateString)
    {
        $dateString = str_replace(array('|', ':'), array('_', ''), $dateString);
        //file_put_contents("$dateString.jpg", $data);
        return true;
    }

but it worked neither - still empty response. How can I return response like this stdClass() ? Or only integer value 1 or 0?

The solution is to add die()

public function indexAction()
{
    $server = new Zend_Amf_Server();
    $server->setProduction(false);
    $server->setClass('Application_Model_Amf');
    $response = $server->handle();
    echo $response;
    die();
}