When I add Twitter RSS it throws an error


When I add Twitter RSS Feed URL it throws the below error, but the same works for other RSS feeds from cnn and msnbc. Can you please check and let me know. I have set the proxy details of proxy server in web.config.
http://twitter.com/statuses/user_timeline/61810471.rss does not appear to be a valid RSS feed. If the feed is valid, please ensure your proxy server settings are correct if you use a proxy server.
Error returned from FeedReader: Object reference not set to an instance of an object.:SmilingGoat.Syndication