Java sample for SSO using JAAS on XP SP2, did anybody get it to work?

[Bajpai, Atul]

Hi all,
I am using a JAAS sample to try SSO on windows. My problem is When I use
the Krb5LoginModule I am always prompted for a username and password. I
want my app to get the kerberos ticket for the currently logged in user
(which is me) without being prompted for username/password. To
understand the problem I set debug=true and following is the output I
get before I get prompted for username/pwd
===================================
Debug is  true storeKey false useTicketCache true useKeyTab false
doNotPrompt false ticketCache is null KeyTab is null refreshKrb5Config
is true principal is null tryFirstPass is false useFirstPass is false
storePass is false clearPass is false
Refreshing Kerberos configuration
Principal is null
null credentials from Ticket Cache
===========================
My question is 
1) Does this mean that ticket cache cannot be found hence a ticket could
not be found or just that the ticket cache is empty?
2) How do I find out where my ticket cache is and what it has?
3) When prompted for username/pwd, if I supply either mine or a test
account username/pwd, my login succeeds and I get back a subject from
the logincontext where I can see a kerberos ticket as part of the
private credentials. What could be the reason for my sample app not
being able to get a kerberos ticket for the currently logged in user
without prompting for username/pwd?

Seems like some of you have dealt with JAAS on windows before so I'll
really appreciate any pointers I can get on this.

thanks