Hi everyone, hope someone could help me

I just installed the last version of OSClass 2.0RC6 on my private dedicated server (Online.net DEDIBOX with Debian).
Everything is ok, the website is working and admin panel is ok.
I downloaded the french 2.0 translation zip file and i tried to install it.
If i use the "add a language function", i take the zip file and i have an error: 'the zip file is invalid'
I tried with swedish one, same error. I downloaded the french file twice, same error and the zip file is ok using winrar, winzip or windows zip support.
If i upload using FTP protocol the fr_FR directory in /oc-includes/translations/ i can't see the french language in "Manage Language function".
What can i try to solve this problem ?
Friendly
Christophe