Restoring Disk

I had an Acronis full backup of my Operating system drive. I think one was a 2014 Acrosis version and the others (including some incremental backups were 2015. I needed to restore my OS (Win 8.1). so I activated the disk restore function and got an error saying that it could not open the file. It might be corrupted. I then checked all the backup files and they were OK. All showed green checkmarks. So I figured maybe I should not try to restore over a network so I connected my external drive to the current computer and tried the process again. Same error. So I then tried to restore the disk from the Acronis boot DVD. It couldn't see my backup drive. I never had this much trouble with 2014.