CRM/Campaigns contacts synchronisation problem

CRM/Campaigns contacts synchronisation problem

Hi,

I've successfully set up a synchronisation process for my contacts from CRM to Campaigns but there's a problem: what I have for "Prénom" (which is first name) in CRM does not appear in Campaigns. Instead of the first name, it's the email adress that appears.  

Example with contact "Louise Michel" (fn=Louise, ln=Michel):

- in CRM I have...

Nom: Michel
Prénom: Louise
Adresse mail: louise@michel.fr
(everything's correct)

- but in Campaigns I have...

Nom: Michel
Prénom:  louise@michel.fr
Adresse mail: louise@michel.fr

So why does it appear that way ? Why do I have an email adress instead of a first name ? I could correct it myself but I would need to do it for every contact and with the everyday synchronisation I'm afraid it will cancel my modifications...

What can I do ?

Thanks for your help.