Use Veritas to import it into the library, inventory it and add it to the appropriate media set.
You might also consider going to the devices tab, right clicking on the drive, select properties, go to cleaning tab and see how long it's been since the last cleaning. In a library, you can't manually insert the cleaning tapes. You have to:
1. Import a cleaning tape and run a cleaning job
2. Have a cleaning tape always in the library and the library will use it as needed.
If the cleaning statistics don't show a cleaning has been done, then one hasn't been done. It's not like a single slot tape drive where the stats aren't updated unless you manually update them. Libraries automatically update the cleaning stats.
Hope this helps
---cheers
shirmal