Windows Vista Ultimate Backup to Network

When I try to set up a back up to a network drive(Buffalo Technologies
Linkstation - ethernet drive) I select back up to network location and I
browse. It finds the drive no problem however after I select it and try to
continue it asks for a user name and password. I have tried my Vista username
and password and I tried no entry. It comes back with no mapping between all
acount names and security ID was dine(0X80070534) Please ensure that the
network location is valid. the drive has no password and the only user name
is the logon name to get into the drive configuration utility. I can selct
the netwrok panel and view , write and read from the drive with out any names
or passwords. HP has been no help nor has buffalo technologies. I am running
the 64 bit ultimate. How can I resolve this.