Sorry for my bad englixh, but I am french

I use joomla 2.5 and virtuemart 2.0.24 and Falang for my main menu.
I have a multilinguage joomla site and also virtuemart in french, italian, spanich and English.
> The first language is ENGLISH
> When i buy a product (Cart) and go to "Register and checkout":NO PROBLEM
> For example my url is: http://www.mywebsite.com/my-cart
When I try to buy a product in a different language (Italian, French...):
> When i buy a product (Cart) and go to "Register and checkout", my website put a bad url :
> For example : http://www.mywebsite.com/mon-panier AND NOT the http://www.mywebsite.com/fr/mon-panier
> So I have a 404 on each different language: italian, spain... (not in english the principal language)
The only solution is to go to the component "com_redirect" and to modify the url. For exemple:
http://www.mywebsite.com/il-mio-carrello TO http://www.mywebsite.com/it/il-mio-carrello
All other menus, pages... are ok with translation, falang...
Do you have an idea about that problem ?
Why website is not online a the moment.
Best regards,
Jerome