failed to verify krb5 credentials

[abbas.attarwala@gmail.com]

Hello,
I am running the kerberos module with apache 1.3.34 on a ubuntu linux
box.

When i try to access the website hosted by apache, i get the username
and password prompt box, but on entering the correct credentials, the
box stays there and keeps on asking for username and password.

On checking the error_log file in apache i found this:

failed to verify krb5 credentials: Server not found in Kerberos
database

On entering some wrong username and password this is what i get
krb5_get_init_creds_password() failed: Client not found in Kerberos
database

what am i doing wrong?

keytab file? wrong realm? 

my kinit works fine.