CMS RSS feed stopped working
 

I haven't updated my forum's software since 4.0.3 came out a while ago, but a few weeks ago the RSS feed from my forum stopped working (http://www.checkcheckonetwo.com/foru....php?type=RSS2). It used to give me new forum messages, and even though there are new messages each day, it doesn't show them anymore.

How do I fix this?