Hi Febby,
Put the tape in the drive & go to the Devices section. Right-click the device in question and choose Inventory. Go to the Job Monitor section and wait for it to complete. Pop back to the Devices section & right-click & choose Catalogue this time. Again, wait for the job to complete on the Job Monitor section. You can now view the entirety of the tape's content, providing an error didn't occur - from this you can work out where the original data was stored & locate that part in the Restore's selection section.
Hope this helps
Andy