Log in as an administrator with permission to change the configuration.
Change to the /etc/opt/SUNWics5/cal/config directory.
Save your old ics.conf file by copying and renaming it.
Edit the ics.conf file, setting the following parameter:
service.http.allowadminproxy = "yes"
Save the file as ics.conf.
Restart Calendar Server for the new value to take effect.