How do you replace it (mailslot or by just removing/inserting tapes)? It sounds as you are missing reset of the library.

Is there really a need to reset the library. I remember using an ADIC Scalar i500 and this device doesnt need to do a reset, simply an inventory will show the new volumes on the list. In any case, with SunC4, I already did the inventory and the reset using the NW Admnistrator GUI but this still doesnt show the volumes' and their barcodes on the volume name (Its configured to use barcode as volume name). I did the reset though using nsrjb -HEv and this works.

With i500 I used mailslot and that worked fine. Certain libraries do not communicate well when there is element status change outside certain parameters so you need element status reset for those (HE).