- Manipulation Token Error

hi all,

I can’t change root password because in my VPS the SSH console gives me:

$ SSH -p xxxx2 username@ipaddress username@ipaddress’s password:
Last login: Thu Jan 9 11:46:58 2014 from dynamic-adsl-xxx.xxx.xx.it WARNING: Your password has expired. You must change your password now and login again!
Changing password for username.
(current) UNIX password:
passwd: Authentication token manipulation error passwd: password unchanged Connection to xxxxxx closed.

how I fix this problem?
thanks in advance

regards