Redirection for dynamic url

Hello,
I’m having trouble with dynamic url redirection setup. It doesn’t seem to work :
/formContact.php?lang=De to http://www.sct-ceramics.com/de/kontakt-sct/ is set up in the admin page, I checked in database, but it’s not working.
And now I can’t set up any /formContact.php redirection neither.
D’you know why ?

WordPress : 3.9.1
Plugin : 2.3.6

Thank you.

https://wordpress.org/plugins/redirection/