Error when changing kerberos password

["Marcelo Magno T. Sales" <marcelo sales sefaz pe gov br>]

Hi,

I have setup my FC6 box so that users can authenticate against Active 
Directory using kerberos. This is working ok.
The first time I tried to change my AD account's password, it worked fine, but 
from the second time on I get the following error:

[marcelo sales sf002698 ~]$ passwd
Changing password for user marcelo.sales.
Kerberos 5 Password:
New UNIX password:
Retype new UNIX password:
Auth error: Authentication error ()
passwd: Authentication token manipulation error

This was right after I had successfully changed the password and no system 
configuration was modified between the two attempts. What may be causing this 
error?

Thanks,

Marcelo