I tried to subscribe to your Feedburner feed and got the same error from iTunes as when I tried to subscribe through the iTunes Music Store. Have you migrated your Feedburner account to Google yet? I know some people have reported problems due to that. If not, I’d check to make sure that your Feedburner feed is pointing to the correct source feed, and also check to make sure that the necessary podcast features are enabled in Feedburner. I think the error that iTunes is reporting is ’cause it can’t find any podcast enclosures in your feed. If you want to e-mail me, I’ll see if I can help you out with the problem.