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

PROBLEM:
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Starting backup at 19-JUL-2014 09:30:56
current log archived
allocated channel: ORA_SBT_TAPE_1
channel ORA_SBT_TAPE_1: SID=1899 device type=SBT_TAPE
channel ORA_SBT_TAPE_1: NMO v5.0.0.0
sent command to channel: ORA_SBT_TAPE_1
channel ORA_SBT_TAPE_1: starting archived log backup set
channel ORA_SBT_TAPE_1: specifying archived log(s) in backup set
input archived log thread=1 sequence=27006 RECID=56462 STAMP=853298699
channel ORA_SBT_TAPE_1: starting piece 1 at 19-JUL-2014 09:31:00
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03015: error occurred in stored script thqr20_backup_arch
RMAN-03009: failure of backup command on ORA_SBT_TAPE_1 channel at 07/19/2014 09:32:35
ORA-19506: failed to create sequential file, name="thqr20_arch.a4pdp8uk_1_1", parms=""
ORA-27028: skgfqcre: sbtbackup returned error
ORA-19511: Error received from media manager layer, error text: lnm_index_cfx_connect retry failed.  See privious error messages. (3:3:11)

SOLUTION:
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Check the nsr_client in your rman backup script