Most tape libraries have a bar code reader, used to read a special bar code on the tape's label. (i.e. a paper sticker on the same end as the red write-protect switch).
The idea is that the library can read the bardcode and know the tape's ID without having to mount & read it. Makes things a lot faster, and saves on tape & drive wear.
When you "inventory" a library, the library with mount, read, and identify each tape. With a "scan", the library will try to read the barcode of each tape. If you have the labels setup right, you get the same result - only a whole lot faster.
Your original message seems to indicate that you don't have a library, but rather a single drive. If that's the case, something else is going on. Backup Exec typically wants to be in control of tapes - when a job starts to run, it will ask you for a tape.. sometimes even a specific one. Just inserting a tape sometimes isn't good enough, becasue BE wants something else.
Also keep in mind that I've seen cases where a brand-new-never-used tape will cause problems until you at least do a "quick erase" of that tape. Rare, but may be helpful.
