Selecting 'Diagnose Job' on the job shows the following entry "Media_Name does not contain required data"
This is because the "Source Storage" option of the backup job is set to a device that does not contain the media to be read.
Changing this to the device that holds the media will resolve this issue.
For more information on this topic, please see the Module 4-Advanced Administration Part Two-Web-based Training
Changing this to the device that holds the media will resolve this issue.
Alternatively changing this option to 'Any Device' will also suffice.