RSS not updating?

[Outrack]

I have a problem where I can successfully add my forum's RSS feed to a reader, but it fails to automatically update when new threads and posts are made after the initial batch (updating manually still works, oddly). I've tested this on multiple readers such as FeedDemon and Reeder, and the users I've asked have all reported the same problem - can anyone help?

My forum's URL is http://ashtear.net/forum/.

[Kindred]

is http://ashtear.net/forum/index.php?action=.xml;type=rss updating correctly (outside of the feed reader?)

is that the url that you have entered into your feed reader?