Sounds like you're having the same problem we're having over here: https://discussions.apple.com/message/21164720#21164720
I'm by no means a pro XML programmer but you do have a small code problem that could maybe be causing a problem.
Try changing this line:
Might not be the fix but worth trying.
You are probably trying to submit the feed at the erroneous URL rd909 has mentioned. Your feed is at
However it won't be acccepted; it has no 'enclosure' tag containing the URL of a media file for your episode, so iTunes wouldn't display the episode anyway.
When you have a query please post the URL of the feed, not its contents.