script won't run in cron but runs on the command line

#!/bin/ksh

now=current
set -x
LOGDIR=/opt/VRTSsfmcs/Backup
THIS_SCRIPT=`basename $0`
LOGFILE=$THIS_SCRIPT_$now.log
MAILLIST="david@itmemphis.com"
MAILSTRING="lnxutil VOM Backup Result $now"

function logger {

        mkdir /opt/VRTSsfmcs/Backup/VOM_Backup_$now
        echo "Creating Logs"

                echo "Creating Logfile"
                mkdir -p $LOGDIR
                exec 1> $LOGDIR/$LOGFILE 2>&1
                mv $LOGDIR/$LOGFILE /opt/VRTSsfmcs/Backup/VOM_Backup_$now
}

function clean {
        echo "Removing old file"
        rm -r  /opt/VRTSsfmcs/Backup/VOM_Backup_last
        echo "Changing file name"
        mv  /opt/VRTSsfmcs/Backup/VOM_Backup_$now  /opt/VRTSsfmcs/Backup/VOM_Backup_last

        echo "Clean Complete"
}

function Do_Backup {
        echo "Running the backup process...."

        /opt/VRTSsfmcs/config/adm/vom_bkup.pl --backup /opt/VRTSsfmcs/Backup/VOM_Backup_$now

        echo "Backup Complete"
}

function mailer {
        echo "Sending Email to david@itmemphis.com"
        cat /opt/VRTSsfmcs/Backup/VOM_Backup_$now/$now.log | mailx -s "$MAILSTRING" $MAILLIST
}

clean
logger
Do_Backup
mailer