Postgresql integration with Microsoft AD

Hi,

I am getting the below error while trying to connect to the postgres
database user with the AD account .We are using kerboros authentication...

DETAIL: Unspecified GSS failure. Minor code may provide more information:
Request ticket server <service principal> not found in keytab (ticket kvno
6)

We have created the service principal in the AD and also placed the keytab
file in the postgres db server.

We verified the kvno is the same in the service principal and the keytab
file..Also verified the service principal name in the keytab file using
ktutil command and it is the correct one..

What could be the reason for this error ?

Command trying to connect to the postgresql db :

psql -U <AD username> -h hostname -d postgres

The same AD user is created in the database also...