Windows 8.1 backup- Error

I am getting an error when I attempt to make a backup to a ReadyNAS (running RAIDiator 4.1.14, ReadyNAS 1100 hardware) from Windows 8.1 using the wbAdmin start backup command in PowerShell:

wbAdmin start backup -backupTarget:\\READYNas\backupshare\backup -include:C: -allCritical -quiet


The error:

The backup operation stopped before completing.
The backup operation stopped before completing.
Log of files successfully backed up:
C:\Windows\Logs\WindowsBackup\Backup-29-05-2015_14-01-35.log

Log of files for which backup failed:
C:\Windows\Logs\WindowsBackup\Backup_Error-29-05-2015_14-01-35.log

The version does not support this version of the file format.


I am aware of the following post from the past, which did not receive any responses from the community:

http://www.readynas.com/forum/viewtopic.php?f=4&t=68284&p=379551&hilit=+Windows+8+backup+#p379551


Hopefully, someone here can tell me how to get the file backup working to a ReadyNAS...

Thanks in advance,
Mike