为什么我没有得到joomla组件中的paypal响应？

I have a script for paypal ipn. i send data, but I don't receive response, but....I don't understand why.

My code:

<input type="hidden" name="notify_url" value="http://www.website.com/index.php?option=com_component&task=response" />

Controller:

function __construct()
    {
        parent::__construct();

        $this->registerTask('changeSubscription','changeSubscription');
        $this->registerTask('submitsubscription','submitSubscription');
        $this->registerTask('response','response');
    }

public function response()
    {
          //Response from paypal 

    }

I if access that url directly, works, but when I use paypal, it doesnt go in response function, I know that beouse sends an email when is there.

Need help to find why....

Thanks!

About my knowledge return_url must be open url, because paypal return values must be valid url.

Check the following settings:

1. Your Paypal menu must be access level in "public" from joomla menu

2. Try to print error_log

3. function processIpn() { } .you will get any errors