Thanks for reply @7bit,
Finally, with your answer i better understand my error/problem.
When i change my layout with sudo dpkg-reconfigure keyboard-configuration
i can choose if i want to use a ISO or ANSI layout, and after, i can choose between french or usa.
My problem is not simple, i have a french ISO layout keyboard integrated with my dell laptop, and i want to use the noppoo with usb. It seems i cannot obtain the ISO and ANSI layout at the same time in ubuntu.So when i change to switch usa or french layout, the physical position for key is the same (ISO or ANSI) :/
I cross-post my problem on askubuntu :http://askubuntu.com/questions/149530/h ... a-ansi-lay