Apache2 and serving directories underneath a symlink

For reasons best left unexplained (because they make my head hurt), I have a machine whose /opt directory tree is a symlink: /opt -> /otherdir/opt I need apache2 to serve files under the /opt tree (/opt/webapp/htdocs), and they need to be accessed by that path name, rather than their "real" path (/otherdir/opt/webapp/htdocs). When I try to open the site in a browser, I get a 403 "Denied" error. The log message that appears is this: