Can’t login to Amazon Prime Instant Video

Hello,
i’ve installed the Amazon Prime Instant Video addon on Kodi 17, and everything went fine.
But now, when i try to login, i always have the same message : login failed, check your credentials.
I have an Amazon Prime Video account to which i access without issues using Firefox browser.
Maybe it’s because of my italian email address, since the Kodi addon is Uk/De/Us ?
I hope someone can help me.
Thank you in advance and best regards,
Luca