Cannot add collections?

Hi,

when I try to add a new collection from a RSS feed on our server hostet by us i get the following error:

iTunes U could not update the content because iTunes U could not connect to the server hosting the specified feed or resources

The content is up and running, we get direct access to the file but for some reason the public site manager says its not there.

Anybody else with the same problem? Is it a server issue at Apple?

-daniel-