Scanning from Kyocera printers to Windows 2008 R2 share.

We are migrating from Windows SBS 2008 server to a Windows SBS 2011 environment which includes a new Windows 2008 R2 server. Our Kyocera printers (TASKalfa 420i, KM-6030, and TASKalfa 4500i) used to be able to scan to an SMB share on our Windows 2008 SBS server just fine. However, when I try to scan to our new 2008 R2 file server (with the exact same share permissions and file structure) I receive a test failure on the printer and I see this error in the event log of the file server:

Event ID: 4625
An account failed to log on.

Subject:
Security ID: NULL SID
Account Name: -
AccountDomain: -
Logon ID: 0x0

LogonType 3

Account for Which Logon Failed: NULL SID
Account Name: scanuser
Account Domain: KM-NETPRINTERS

Failure Information:
Failure Reason: Unknown user name or bad password.
Status: 0xc000006d
Sub Status: 0xc0000064



If I simply switch the server IP address on the Kyocera back to the old server IP, it works perfectly fine. How can I fix this?

Thank you