Enclosure not showing up in podcast rss feed

I’m doing a radio show (podcast) on my blog. I set up a separate category for posts including links to the mp3 files within each post. When I view the RSS2 feed for that category, there’s no enclosure tags in the feed items.

I’ve looked through the codex for answers and also other blogs, but all I find is info saying that WP is supposed to handle the enclosures automatically.

I’m using WP 1.5.2 with the pretty urls enabled. The podcast category on the site is https://www.gadgetizer.com/gadgets/radio/ and the feed is at https://www.gadgetizer.com/gadgets/radio/feed/rss2/

My hosting is standard setup with PHP 4.4.1 and MySQL 4.0.25 if that makes a difference

Is there something I’m doing wrong? As I said above, my understanding is that WP handles enclosures automatically.

If someone could offer suggestions I’d really appreciate them. Thanks.