RMAN receives: OSB error: UUID not found OB cached object manager

Question

I am receiving an error when backing up :
Starting backup at 17-MAR-2009 10:00:00
allocated channel: ORA_SBT_TAPE_1
channel ORA_SBT_TAPE_1: sid=137 devtype=SBT_TAPE
channel ORA_SBT_TAPE_1: Oracle Secure Backup
channel ORA_SBT_TAPE_1: starting full datafile backupset
channel ORA_SBT_TAPE_1: specifying datafile(s) in backupset
input datafile fno=00001 name=+DGROUP1/seattle/datafile/system.826.679693097
channel ORA_SBT_TAPE_1: starting piece 1 at 17-MAR-2009 10:00:02
RMAN-03009: failure of backup command on ORA_SBT_TAPE_1 channel at 03/17/2009 10:02:57
ORA-27191: sbtinfo2 returned error
Additional information: 2
ORA-19511: Error received from media manager layer, error text:
sbt__rpc_cat_query: Query for piece 07ka4pt2_1_1 failed.
*(Oracle Secure Backup error: 'UUID not found (OB cached object manager)').*
Prior to this (when everything was working) I merely tried to re-label a tape. Why this has caused the problem I do not know but I can't seem to fix it.
Does anybody know what has happened and what the fix is?
On the HTTP administration page, when I try to configure the device I get the following error message:
Error:      cannot read location object associated with device - UUID not found
It looks as though the device definition has been corrupted some how.

Answer 1

The fix has been found (from Oracle Support). The cause is not yet understood.
I document it here for others who may run into the same problem.
It seems that the device "went missing". The fix was to add it.
ob> mkloc dat72
It is still being investigated and I will update the notes when I am in possession of more information.