When adding additional backup disks to your Windows SBS 2011 server backup, you may get an error stating:

Quote

The filename, directory name, or volume label is incorrect.

The problem occurs with the SBS console and when running the Server Backup snap-in.

Workaround

You can work around this issue by manually adding the backup disks via the wbadmin command line tool.

1. Connect the disk you wish to add to the system. Open up a command prompt.
2. Fetch a list of available backup targets by running:

   wbadmin get disks

   You need the DiskID displayed of your backup disk.
3. Add the disk to the backup pool by running:

   WBADMIN ENABLE BACKUP -addtarget:"{DiskID}"

   Replace the DiskID with the one you have, for instance:

   WBADMIN ENABLE BACKUP -addtarget:"{aa123d14-bba0-1dd9-0d93-80aaaa6bbb63}"

   Note that the quotes around the ID are optional although it prevents from getting the error message Bad numeric constant