Kerberbos Authentication on MOSS

Hello All,

We have MOSS containing application webparts which makes web service calls
onto another system where the web services and application are installed. We
use kerberos authentication for the communication between MOSS and our
application server.

When HTTP spn (service prinicipal name) is defined for domain user account
web service calls from MOSS server to our application server are failing with
401 unauthorized access errors. Please note: If we directly use the webpart
from the MOSS server i.e. browse the website with application webpart from
MOSS server calls to web services are going through.

Application web services are using application pool which is configured
using "Network Services".

Any inputs would be greatly appreciated.

Thanks in advance.