facebook shows "not found." when clicking the received app requests sent by graph api

just as the title.

I sent a app request to my facebook account by this way.

http://developers.facebook.com/docs/reference/dialogs/requests/

and then, I received a notification on facebook.

says like that: *Johanna Bassam Bassam Haro sent you a re开发者_如何学Cquest in APP_NAME. 9:55am*

when I click*APP_NAME* ( a link). I got this http://www.facebook.com/4oh4.php

I guess there should be a configuration on our app. anyone know what's it? or what I forgot to set? thank you very much