RSS feed does not validate

[dmcagulada]

Moderators Note: Post moved from old thread.

I have the same problem. I've disabled all the plugins and deleted the .htaccess file as well had the server checked out. When I try to validate I get this:

Sorry

This feed does not validate.

• Server returned HTTP Error 404: Not Found
  
• line 7, column 16: lastBuildDate must be an RFC-822 date-time:
  

  <lastBuildDate></lastBuildDate>

Source: http://www.seoswissarmyknife.com/feed/rss

1. <?xml version="1.0" encoding="UTF-8"?>
2. <rss version="0.92">
3. <channel>
4. <title>» Page not found</title>
5. <link>http://www.seoswissarmyknife.com</link>
6. <description>Long time practitioner of SEO in Maine, there's nothing random about SEO, SEM and Internet Marketing through competitive intelligence analysis.</description>
7. <lastBuildDate></lastBuildDate>
8. <docs>http://backend.userland.com/rss092</docs>
9. <language>en</language>
10. <xhtml:meta xmlns:xhtml="http://www.w3.org/1999/xhtml" name="robots" content="noindex" />
11. </channel>
12. </rss>