Well, here my new procedure...and it's work !!

Code:
dd if=/dev/zero of=/mnt-system/knoppix-data.img bs=1M count=2048  
losetup /dev/loop6 /mnt-system/knoppix-data.img
mkfs.ext2 /dev/loop6
losetup -d /dev/loop6
mkdir /mnt-system/work
mount -o loop=/dev/loop6 /mnt-system/knoppix-data.img /mnt-system/work
rsync -ax /KNOPPIX-DATA/ /mnt-system/work
e2fsck -fy /dev/loop6     # I don't know if it's necessary

Bye