Error in Deleting Expired Backup from repository.

 Hi

I am trying to delete expired backup with following rman block but getting the below error.

run
{
allocate channel t1 type 'sbt_tape' parms 'ENV=(TDPO_OPTFILE=C:\Program Files\Tivoli\TSM\AgentOBA64\tdpo.opt)';
allocate channel t2 type 'sbt_tape' parms 'ENV=(TDPO_OPTFILE=C:\Program Files\Tivoli\TSM\AgentOBA64\tdpo.opt)';
change backup of controlfile crosscheck;
delete noprompt backup of controlfile completed before 'sysdate-35';
}

List of Backup Pieces
BP Key  BS Key  Pc# Cp# Status      Device Type Piece Name
------- ------- --- --- ----------- ----------- ----------
3095    3089    1   1   EXPIRED     SBT_TAPE    c-3595989929-20090219-00
3317    3315    1   1   EXPIRED     SBT_TAPE    c-3595989929-20090302-00