OS X Server bound to Active Directory, but OS X Clients who are logged in as AD users prompted for username when connecting to OS X server file shares OS X Server bound to Active Directory, but OS X Clients who are logged in as AD users prompted for username when connecting to OS X server file shares

The OS X server appears to be bound to AD with no problem.
This OS X server is ALSO running Apple's Open Directory (as we have a number of Mac workstations still on OpenD. that have yet to be migrated to ActiveD.)

Windows AD users can browse the OS X File Server shares no problem

However, the Mac OS X Workstation users who are logged onto their Macbooks as AD users get prompted for username+password when they try to browse the OS X Server file shares.  They can only connect using an Open Directory username+password.  They CAN NOT connct using the Active Directory credentials.

These same Mac workstation users can browse all the Windows domain file servers without needing to enter username+password.  

Any idea why the OS X Server is not treating an OS X AD file-share client the same way as a Windows AD file-share client?
Ok, to answer my own question, it appears that if the Mac client uses AFP to connect to the MAC OS X Server, then it will not use AD.

If I instead browse the the Mac OS X server using SMB  (eg, connect to: smb://servername )  - then it will connect as an AD user (with no prompting for username/password) and will list all the shares that AD users have access to.