Errors trying to connect Oracle/RMAN with TDP

Please help. Our project is light on RMAN skills. Please can someone advise
us.

Our environment is

Solaris 2.6
TDP 2.1.10
Oracle 8.1.6

We get this error when attempting to do a RMAN backup:

RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03007: retryable error occurred during execution of command: allocate
RMAN-07004: unhandled exception during command execution on channel ch1
RMAN-10035: exception raised in RPC: ORA-19554: error allocating device,
device
type: SBT_TAPE, device name:
ORA-19557: device error, device type: SBT_TAPE, device name:
ORA-27000: skgfqsbi: failed to initialize storage subsystem (SBT) layer
Additional information: 4110
ORA-19511: SBT error = 4110, errno = 0, BACKUP_DIR environment variable is
not set
RMAN-10031: ORA-19624 occurred during call to
DBMS_BACKUP_RESTORE.DEVICEALLOCATE
Recovery Manager complete.


And here's the script we are trying to run:

run {
2>     allocate channel ch1 type 'sbt_tape' parms
3>       'ENV=(DSMI_ORC_CONFIG=/usr/bin/dsm.opt,
4>            DSMO_AVG_SIZE=50)';
5>     backup database;
6>     sql 'ALTER SYSTEM ARCHIVE LOG CURRENT';
7>     }

We believe we have executed the 'link' operation from RMAN to TDP - maybe
not??
What should we check?
What can we test?
Any help greatly appreciated.

Chris Campbell
Tivoli Services Team    ITS, IBM Global Services
IBM Ireland, 24/32 Pembroke Road, Dublin 4, Ireland
Phone  :  +353-1-815-4146    Internal 50-4146     Fax +353-1-815-4304
Internet :  chris_campbell AT ie.ibm DOT com