You can also request the code from the registry directly from their website at http://www.dns.be from the bottom of their results page after you look up your domain in their whois.
Launch the change owner operation on Gandi's website. Do not enter an authorization code (Click the button that allows you to proceed without it).
Gandi will send the owner a confirmation email. When Gandi has gotten the confirmation from the old owner, we will inform DNS.BE (the .BE registry) of the request.
DNS.BE will then send an email to the owner of the domain name that contains an authorization code.
The owner can send this code to Gandi's support team by email using the online support contact form (or enter it themselves from their list of operations in progress).
If necessary, Gandi's support then relaunches the owner change (trade) with the code that has been provided.