Feed dialog generating errors with iOS SDK
The page http://developers.facebook.com/live_status reports the issue today at 16:49 (GMT+1)
To follow the issue : https://developers.facebook.com/bugs/295765603772094
I don't think you are doing something wrong.
Just experienced the same problem with with my working app.
Most likely an issue on the side of facebook
You can use direct REST API or Graph API calls that are working now.