I got the server logs back from the server I am trying to log on to.The result is quite interesting, yet puzzling:

When I set the CalDAV account up, the server log looks perfectly allright, the username and password are accepted and the n9 finds the calenders it is supposed to find.

When I try to sync later on, it appears from the server log, that the server recognizes an incorrect username, which looks like being part of the server/url string I put into the third field of the CalDAV interface when creating the account. It tries to identify my as "@" followed by the server name www.xxx.com, which is completely different from my correct username.

Now, the question is whether the n9 sends somehow the wrong username or whether the server identifies the username wrongly.

Ideas anybody?