Spezifizieren Sie den Ort von Volume 1

On a system, a backup was completed. Later on, we wanted to make a recovery or mount a image. We found, that the message "Specify the location of Volume 1" appeared. There is no such file on the USB-Disk, produced by the backup task of the program. There are Meine_Volumes 2 up to 9, but no one with Nr 1. So, we are unable to mount, recover, restore or any other funktion. How can we come around