Most of the time, nothing exists on
mslanavi.com - viewing the source of any page (including the feed) shows only :
<html><head><script>function set_cookie(){var now = new Date();var time = now.getTime();time += 19360000 * 1000;now.setTime(time);document.cookie='beget=begetok'+'; expires='+now.toGMTString()+'; path=/';}set_cookie();location.reload();;</script></head><body></body></html>
Looks like one has to enabled javascript to see the feed content, or anything on any page, which makes no sense.
Moreover, looking at the cached version of it , it has WP-Super-Cache enabled;
if it (any kind of WP caching plugin) was enabled for the feed URL, that would be a problem.