knoppix-customize pb

Hello wonderful knoppix world

I try to knoppix-customize the KNOPPIX_V3.4-2004-05-17-EN.iso 
(in order to get fr keyboard ;) i copied to knoppix.iso

But, whatever i try i got a "Error reading image. Aborting"
I do the first example given in the man:
$ ls -l knoppix.iso
-rw-r--r--    1 al2      al2      723064832 2004-07-22 16:38 knoppix.iso

$ knoppix-customize --image knoppix.iso --action export_floppy --local_file boot.img
No emulation (can't handle this)
Error reading image. Aborting

I tried, as root, or with absolute path /Big/ISO/knoppix.iso, from the
liveCD with both 2.4 and 2.6 kernel , and its always the same error :(
I checked the MD5 (good) and the CD is working !

Any suggestion welcome.

Regards
Alain