Q : Sometimes the application doesn't bring back any events
A : If you are on a very dynamic network (your IP change every page you refresh) you should ask your Sun Calendar server admin to disable ipsecurity.
To know if you have this problem look in your server logs for this kind of lines :
cshttpd[ZZZZ]: General Warning: ipsecurity - client Y.Y.Y.Y attempted to use session SSSSSSSSSS belonging to X.X.X.X
To change the configuration of your server edit your "ics.conf" file to have :
service.http.ipsecurity = "no"