Differential Wizard cannot find object to backup

I made a 120gb backup of 1TB hadrdrive to a second 1TB drive.
Best I can tell it looks good. HDM 11 Suite but when I click on 'ABOUT' it says

Paragon Hard Disk Manager™, version 10.0.17.13908 (30.08.11 ) Suite


Anyway, I select ARCHIVES and right click on the current backup.
I then select DIFFERENTIAL BACKUP. And recv the encl error screen.

I do not recall this problem with b&r11 free, but this is my first time using Suite11 to do a differential.

Thanks, Howie

 

To clarify the full backup was done with Suite 11. I am not trying to do a differential against a b/u done with a different level of Paragon. This should all be the HardDisk Suite 11...