RMAN does not read the TDPO_OPTFILE Environment Variable, SBT error = 7011, errno = 2534

We try to run a RMAN Crosscheck with automatic Channel Allocation. We receive the following Error :

RMAN> crosscheck backup of database;

RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of crosscheck command at 01/20/2014 11:46:50
ORA-19554: error allocating device, device type: SBT_TAPE, device name:
ORA-27000: skgfqsbi: failed to initialize storage subsystem (SBT) layer
Linux-x86_64 Error: 2534: Unknown system error
Additional information: 7011
ORA-19511: Error received from media manager layer, error text:
   SBT error = 7011, errno = 2534, sbtopen: system error

In the tdpoerror.log file we see the following Message :
01/20/2014 11:46:50 TID<23185>  ==>  ANU2615E Options file '/opt/tivoli/tsm/client/oracle/bin64/tdpo.opt' not found.