Q: Use of unknown namespace: http://www.apple.com/iweb

I have created a website using iWeb 3.0.4. I have added some RSS feeds to the site using the RSS widget. Until recently this worked fine but the RSS feeds no longer display. An error appears in iWeb when it tries to load the feed "The RSS feed source can't be reached. Try again later." I have used http://feedvalidator.org/ to check the syntax of the feed. It is a valid RSS feed but it picks up 2 errors. These are:

Use of unknown namespace: http://www.apple.com/iweb

Missing atom:link with rel="self

Is it possible that these 2 errors are preventing the feeds from loading? If so, what changes should I make to the rss.xml file?