Podpress feed not validating

my podcast was working well until last week now its not validating and my itunes link died.

my website is http://www.dematrixshow.com when i go to validate this happens
http://www.feedvalidator.org/check.cgi?url=http%3A%2F%2Fwww.dematrixshow.com%2Fsite%2F%3Ffeed%3Dpodcast