Using FBs new request Dialogue states:

Accepting a Request

If your user clicks 'Accept' on the request, they'll be delivered to the canvas Link to the applying that sent the request. This URL will contain one more parameter, request_ids, the industry comma delimited listing of Request IDs that the user is attempting to do something about: http://applications.facebook.com/[application_title]/?request_ids=[request_ids]

However, if i recieve to my joomla site inside the facebook canvas. im not able to obtain

$reqId = JRequest::getInt('request_ids') outcome is inside my module....

Would you give a bit more information? What's the URL that you simply deliver to the return adress? What's the title from the component that you're creating/using?