Network share from Windows 2003 Server

I have installed a Windows 2003 server as member server in my domain kp.com
I am able to connect to this new server branch.kp.com using \\branch.kp.com from any computer in the network. However when I use the same UNC from the branch.kp.com server it fails with authentication failure.

I am able to connect using IP address from the same server and it connects without prompting for password.

Any idea?

Regards,
Rasheed