Facebook comments plugin doesn't show comments made on wall posts

According to Facebook, comments made t开发者_高级运维hrough the comments social plugin will post to the user's wall. This is working, but comments subsequently made in reply to such a post on Facebook.com (as shown in this FB dev video: http://csull.in/eMMsDF) don't show up on the site with the comments plugin. I have tried everything I can think of, and while using the iFrame feedback method does work, the fb:comments method does not. Any ideas?