rsync: exclude doesn't work?

[Rob]

Hi,

I use rsync to back up my files, but I want to exclude uninteresting bulk
files in cache directories of netscape, opera and mozilla. After reading
the man pages, I use following call:

/usr/local/bin/rsync \
         --exclude "rob/.netscape/cache/" \
         --exclude "rob/.mozilla/**/Cache/" \
         --exclude "rob/.opera/cache4/" \
         -avzC /home/rob /home/BACKUP

However, the exclude lines seem to be ineffective; all the cache directories
are rsync'ed each time this backup script runs.

Any ideas why that is?

Thanks
Rob.