Acronis TI 11 build 8101 fails with Username/Password for Remote Resource incorrect on Drobo-FS

I've been using my Acronis TrueImage 11 (8101) to do nightly backups of my XP laptop to a USB Lacie drive. That has been working perfectly; however, I've run out of room on that USB drive! I have a Drobo-FS with heaps of space available so I tried to switch my nightly backups to the Drobo-FS (Samba V. 3.4.4).

Acronis fails every time with an error in "Module 1, Error Code 1,015: User name or password for the remote resource xxx is incorrect. Please check your username and password and type it again."

I'm using WinXP to login to my Drobo-FS as a certain user and my Explorer can connect just fine (I can even create/save files to the Drobo under Win Explorer). When I walk through the Acronis Create Backup Wizard, I can select my Drobo-FS shared drive for the 'Backup Archive Location' so Acronis can 'see' my destination. I've tried specifying my user/password on the 'Network Logon' step and I have tried leaving this part blank. Both options result in the same error mentioned above.

I find this to be very peculiar especially since I have been able to use Acronis to save a xxx.cfg file to my Drobo-FS. I know that Acronis can write files to the Drobo-FS so why does it refuse to backup to the Drobo-FS? I've also used Acronis Backup Locations to create a location on my Drobo-FS. This completed successfully and has validated successfully.