Podcast rss feed does not work on ITunes

Podcast rss feed does not work on ITunes

I am using the Itunes application on Windows. I have recently upgraded to
version 11.0.4.4.
I am trying to subscribe to this podcast:
http://rss.rtbf.be/media/rss/audio/c21-best_recent.xml
This podcast is displayed in the list, but it is not updated and the list
of item is not downloaded. It says 'Zero episodes', which is not true. I
am trying to refresh it, etc... but without success.
I do not get any error message or pop-ups.
Does anyone know what is happening and how to solve this issue?
P.S.: Some other podcasts work properly though...