--delete-excluded not working on local rsync

[Jon Gabrielson]

I am using the following command and the excluded 
directory /usr/share/doc/ still appears with all it's contents in the
backup directory when it's contents should be deleted. Is this a bug 
or am I doing something wrong?

rsync --delete --delete-excluded -a -R --exclude="/proc/*" --exclude="/dev/*" 
--exclude="/usr/share/doc/*" --exclude="/backup*" / /backupdir/


Thanks,

Jon Gabrielson