No valid destination disks

I wanted to try upgrading from Windows 7 to Windows 10, so I created full backups of my drives. I have a 128 GB SSD and 3 1 TB HDDs in RAID 5. After upgrading to Windows 10, I tried to restore some of my files from the HDD backup. When I do this I get an error message, “No valid destination disks found for the selected item”. The disk image shows as 1.81 TB in Comodo and my new disk in Windows 10 is 1.80 TB. I’m guessing that the error is caused since the new drive is 0.01 TB smaller than the old one. I don’t understand this because I only want to restore some of the files, not the whole thing. I also tried to mount the drive, but I get a message saying “An error occurred while mounting the selected backup”. In fact I can’t even mount the SSD image because I get the same error. How do I retrieve my data?