Firstly - do you have licensing for Vault?
Vault is meant for regular ejects where you set up profiles to select certain images, volume pools, clients... etc written in a particular date range to be duplicated and/or ejected. Not really worth it if you want to eject every now and then.
Details about Vault option in this manual: NBU Vault Admin Guide .
Really too much to cover in a single post.
If you want to eject a couple of tapes manually and ensure NBU and the robot are both up to date, follow these steps:
Manually select the tapes in the Media section of the GUI, right-click, select “Eject Volume(s) from Robot….”
A new window will open with 'pre-checks' on the list of tapes to be ejected.
After a short while NetBackup will complete the eject pre-checks.
If the list is correct, click “Eject”.
This will eject all the media listed into the Media Ejection Port (MAP/CAP) on the library. Once all media has been moved into the CAP, a pop up will appear asking "Do you want to continue with the eject?". Do NOT click YES as yet.
You can now go to the Library and remove the tapes from the CAP.
Once you have removed the tapes and closed the CAP (wait ±2 mins), click on YES on the above screen.
NB. Only click “Yes” after you have removed the tapes from the CAP.
Once completed, “Eject success” will be displayed.
Click on Close to update Media List.
(Above process corresponds with second part of Andy's post: https://www-secure.symantec.com/connect/forums/eject-tape-media-stk-sl3000-tape-library-data-it#comment-7820411 )