NBU中恢复数据库 报一下错误，请大家帮忙看看啥原因

channel CH00: restoring control file

released channel: CH00

RMAN-00571: ===========================================================

RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============

RMAN-00571: ===========================================================

RMAN-03002: failure of restore command at 02/21/2017 10:27:31

ORA-19870: error reading backup piece /cntrl_36931_1_936134229

ORA-19507: failed to retrieve sequential file, handle="/cntrl_36931_1_936134229", parms=""

ORA-27029: skgfrtrv: sbtrestore returned error

ORA-19511: Error received from media manager layer, error text:

   Backup file not found in NetBackup catalog

这是脚本

RMAN> RUN {

2> ALLOCATE CHANNEL CH00 TYPE 'SBT_TAPE';

3> SEND  'NB_ORA_SERV=backupserver,NB_ORA_CLIENT=p550a_svc';

4> RESTORE CONTROLFILE FROM '/cntrl_36931_1_936134229';

5> RELEASE CHANNEL  CH00;

6> }