in the tarpit -- cannot exclude cache

[Kevin O'Gorman]

This makes me feel really dumb.  I've been using tar(1) since the mid
80's, but it's not going well today.

I'm making backups scripts for my system.  I want to exclude cache
directories, and see that there are three slightly different ways to
do this, any one of which would be adequate for my purpose.  However,
they are not excluded.

I've done a "touch /home/kevin/.cache/CACHEDIR.TAG" to mark the
directory I want to exclude, but it's not getting excluded.
The command runs as root, and the complete command line is

    sudo tar --absolute-names --one-file-system --exclude-caches -czf
treat.home.manual-121011.tgz /home

and changing the type of --exclude does not help.

Somebody please tell me what I'm doing wrong?

-- 
Kevin O'Gorman

programmer, n. an organism that transmutes caffeine into software.