makoto> | installboot: nlist: /usr/mdec/bootxx: symbols not found

It doesn't to seem to be a problem on 'new bootxx', but just in general.
I got the same problem on 20020407-1.5ZC/installation/boot.fs

# mount /dev/wd0d /mnt/usr
# cd /mnt/usr/mdec
# ./installboot -v bootxx /mnt/boot /dev/rwd0a
boot: bootxx
proto: /mnt/boot
device: /dev/rwd0a
installboot: nlist: /mnt/boot: symbols not found
# ls /mnt/boot
/mnt/boot
# ls -l /mnt/boot
-r--r--r--  1 root  wheel  57420 May 19 22:49 /mnt/boot

Sorry for confusion.
Am I doing something wrong ?
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Makoto Fujiwara,