problem with facebook api - Keeps redirecting

I created an application with a name and connect URL on facebook.

I put below code in test.php here (test.php):

include_once 'facebook.php';
$fb = new Facebook('api_key', 'secret');
$user = $fb->require_login();
echo $fb->api_client->user;    
echo $fb->api_client->session_key;

when I go to that page, it takes me to facebook login, after I login it redirects me to same test.php with an auth_token. But it doesn't stop there. For some reason, the script is taking me to facebook again and since I already logged in facebook redirecting me to test.php with another auth_token just like below

/t开发者_StackOverflow中文版est.php?auth_token=76a6eb21b872cdfe787ea85a240905dd&auth_token=597d7532bf53c8ce37cc003bcf7d2905

It never stops there, test.php taking me to facebook again and again :(

Please tell me what wrong??

Thanks a lot

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adda line: $facebook->require_frame();