Error: Feed failed! Causes may be (1) No data found for RSS feed https://www.facebook.com/feeds/notifications.php?id=100008057075260&viewer=100008057075260&key=AWiPMBSOyDT22I-c&format=rss20; (2) There are no items are available for this feed; (3) The RSS feed does not validate.
Please verify that the URL https://www.facebook.com/feeds/notifications.php?id=100008057075260&viewer=100008057075260&key=AWiPMBSOyDT22I-c&format=rss20 works first in your browser and that the feed passes a validator test.