MSL2024 error

[Charles Peechumuthu]

We have MSL2024 LTO3 ultrium 920 tape library running for last one year. It has been working fine till yesterday. No mailslot configured on the library. Yesterday when we refilled the slots (only 1 thru 10 are in use) and mount the magazine thru Arcserve 11.0 ( which mounts in set of 1-8, 9-16..), it mounted first 1-8 slots OK, then while mounting 9-16 (only 9 and 10 slots are in use), Arcserver reported both media as unreadable and Attention LED on tape library started amber flash. Both media are in use for last few months, used once every 14 days. Any way we loaded two brand new media (we use HP C7973A, yellow cartridge) in slots 9-10 and try to mount again. same error.
So we tried to clean the Drive with a HP cleaning media, used only once before (less tahn 3-4 months old). Cleaning fails with LCD panel meesage: Cleaning Drive 1 failed, inv. cartridge

We do not use RMI,no network connection.
But from OCP, going to support and then to lib error log, has no entry.
But Lib Warning log has following entries, several of them
63 00 15 inv. cartridge
84 06 01 Tape Alert Log invalid LUN Init. required
84 04 01 Tape Alert Log invalid LUN Init. required
84 02 01 Tape Alert Log invalid LUN Init. required

same error messages are repeating.

Any clue on what is going on?
We rebooted the library thru OCP. Did not power off the unit manually.
Any help is appreicaited

TIA
Charles