I have run a Mac OS backup without trouble. Mac OS installed is 10.11.6. (El Capitan)

This software will not run a Bootcamp Backup. I have tried various combinations of clicking partitions or disks or operating system and they all give the same error "Selected Partition Does Not Support This Operation"

It supported the Mac backup to external usb 2 tb drive, but will not backup the Windows 10 partition.

Do I need to install 10.12 Sierra?