Facebook Requests doesn't work

I'm trying to gets new user whit Facebook Requests. Unf开发者_JAVA百科ortunally when an user accept the invite from facebook he is redirected to https://www.facebook.com/?request_ids=xxxxxxxxxxx and not to my website. i tryed to pass the userid to facebook but i don't receive any "postback". what it's wrong whit my app? i need to change app settings or is my code wrong?

     <div id="fb-root"></div>
     <script src="http://connect.facebook.net/en_US/all.js"></script>
     <script>
    function invitefacebook(){
       FB.init({appId: 'xxxxxxxxxxxx', xfbml: true, cookie: true});
    FB.ui({
    method: 'apprequests',
    message: 'I invite you in this awesome website!',
    data: '<?php echo $id; ?>'});

    }
    </script>
<a onclick="invitefacebook();">Invite Friends</a>

Thanks in advance :D

Even though it redirects to the facebook.com you can see your application either as an iframe or as a tab inside that url itself.

so you should code your app such that you do something when you get the request_ids in the url..

So do something like this

if(isset($_REQUEST['request_ids'])){
 //here you can get the current logged in FBuser using you SDK 
 //and then just write some code, where you can either store them as 
 //accepted invitation in db or anything as you wish.
}

The above code should present in the page which will be displayed as an iframe when the user is redirected to the app.