Restore files fro image / mounting images - Acronis true Image echo 8 on windows 2003R2 Std Server

I am relative new to my Company and the the former admin
installed Acronis True image echo Server version 8 on the systems.

i'm having some serious trouble with restoring data from an image.
mouting the image fails. When trying to restore specific file from the image
i'm recieving errors. (can not read from image).

the Backup is taken as a disk-image and there where no errors when the task was finished.

I used different targets. (USB Drives, Local hard Drives) for the Backup.

The problem exists for all targets.

I cant restore my data. Backupfiles are useless !!

How big in size can the Tib files be?
My files are around 650 GB. Is this a Problem ? I use High compression.

Need help

Thanks to all

M.Kloke