enabling authentication for login won't work


i’ve installed google-authenticator-pam and added

auth    required        pam_google_authenticator.so     nullok

to the end of


but when typing password, greeter says login failed.
what should i do?

And did you receive an authenticator number on your phone?
EDIT: and reboot after enabling it ??

yes i have on my phone. restarted but it’s not mandatory because i test changes and modify the problems by the root account. changes affect immediately on login process.
some pages said that adding that line above this line:

auth    [success=1 default=ignore]      pam_unix.so nullok_secure

but it’s not existing in /etc/pam.d/common-auth-pc.

note that it works in command line mode but not graphical login.