TI 2014 File Backup fails to create snapshot and cannot find a file

I am running TI 2014 and have set up a file backup. The backup fails immediately when I run it. The log contains the following entries:
-- Backup reserve copy attributes: format tib; need_reserve_backup_copy false;
-- Operation FileBackup started manually.
-- Operation description: Stage Description.
-- Backup reserve copy attributes: format tib; need_reserve_backup_copy false;
-- Priority changed to Low.
-- Failed to create snapshot for backup. 0x616AD0806A6301EF
-- Failed to create snapshot for backup. 0x616AD0806A6301EF
-- Failed to create snapshot for backup. 0x616AD0806A6301EF
-- Create Backup Archive
From:
C:\Users\David\Documents\
C:\Users\David\Downloads\
C:\Users\David\Music\
C:\Users\David\Pictures\
C:\Users\David\Videos\
C:\Users\David\AppData\
C:\Users\David\Contacts\
C:\Users\David\Desktop\
D:\Music\
D:\Photos\
D:\videos\
To file:
"FileBackup_full_b7_s1_v1.tib"
Compression:
Normal
Exclude:
System files
-- Error occurred while backing up. (0x40019)
Tag = 0xCE542E14DA203B82
The specified file does not exist. (0x40011)
Tag = 0x497A70FDD71A3FC1

I just created this backup scheme, but the file it tries to create, "FileBackup_full_b7_s1_v1.tib", seems to imply that it is not the first backup in the chain.
Disk backup is working fine. I need to make File Backup work.