There's no point in the world in posting just the filename! Please always post the full URL of your Store page and the feed. I've managed to do some detective work: somehow you've managed to get your podcast into the Store twice, at
https://itunes.apple.com/gb/podcast/light-1.0/id80233102?mt=2
which uses the feed at
http://www.mediabench.com/Light_WEB/LightXMLFeeds/Light_Feed.xml
and
https://itunes.apple.com/gb/podcast/light-1.0/id79879818?mt=2
which uses the feed at
http://www.mediabench.com/Light_WEB/LightXMLFeeds/Light_1_Chap_2_Feed.xml
The contents of the feeds seem to be the same. Both feeds have 29 episodes and these show when subscribing. Currently the Store is suffering from a bug where only 20 episodes are showing (Apple are working on it). Most people's podcasts are sorted by date with the latest at the top, but you have used the 'itunes:order' tag to over-ride the dates, and have started numbering at the earliest podcast. Consequently the episodes are displayed in the Store (though not when subscribing) in this order, with the oldest on top. So it's episodes 21 onwards which have been lost. (Confusingly, the Store shows all your episodes as dated as 6 May 2009, I don't know how you've managed that (though your pubDate tag dates are not correctly formatted, please see this note).
It's up to you whether you want your episodes listed in date order or reverse date order, though most people find the latter more convenient as it brings the latest episodes to the top; but while you are listing them in date order and until Apple sort out this problem I'm afraid your recent episodes are not going to show. However subscribers are seeing everything normally, as users of the iOS Podcasts app should be.
