archive backup error 11.1 database

Dear Experts,

Below is the script which are using to take archive log backup.

[oraprod@SSSTINDCPODB02 log]$ cat /home/oraprod/archivebackup.sh

#!/usr/bin/ksh

#set -x

######## Variables #######

##########################

RUNTIME=`date '+%H%M%S_%d%m%Y'`

RUNDATE=`date '+%d%m%Y'`

###### Input Values #######

###########################

ORACLE_HOME=/u02/PROD/db/tech_st/11.1.0

ORACLE_SID=SSSEBSPR

ORACLE_DB=SSSEBSPR

LOGDIR=/u02/PROD/db/tech_st/11.1.0/backup/log

BACKUP_BASE=/sssterp_bak/prodbkp

PATH=$ORACLE_HOME/bin:$PATH:/usr/local/bin

NLS_DATE_FORMAT='DD-MM-YY HH24:MI:SS'

export ORACLE_HOME PATH NLS_DATE_FORMAT NODE_NAME ORACLE_SID

# Specific settings #

#########################################

export LOGFILE=${LOGDIR}/DB_${ORACLE_SID}_${RUNTIME}.log