Redhat disk free NULL2

RAM, traffic, Processor, ... is monitored with SNMP with success. But senssor "SNMP Disk free" is not working.

If I use SNMP V1 the error message is "NULL2", if V2 error message is:

"#N SNMP_EXCEPTION_NOSUCHINSTANCE223"

It is probably somehting missing in my snmpd.conf like in this thread: Can't use SNMP Linux disk free

Would you help me to know what is the missing line? I tried to add "includeAllDisks 10%".

###############################################################################
# disk checks
#

# The agent can check the amount of available disk space, and make
# sure it is above a set limit.  

# disk PATH [MIN=100000]
#
# PATH:  mount path to the disk in question.
# MIN:   Disks with space below this value will have the Mib's errorFlag set.
#        Default value = 100000.

# Check the / partition and make sure it contains at least 10 megs.

#disk / 10000


# % snmpwalk -v 1 localhost -c public .1.3.6.1.4.1.2021.9
# enterprises.ucdavis.diskTable.dskEntry.diskIndex.1 = 0
# enterprises.ucdavis.diskTable.dskEntry.diskPath.1 = "/" Hex: 2F 
# enterprises.ucdavis.diskTable.dskEntry.diskDevice.1 = "/dev/dsk/c201d6s0"
# enterprises.ucdavis.diskTable.dskEntry.diskMinimum.1 = 10000
# enterprises.ucdavis.diskTable.dskEntry.diskTotal.1 = 837130
# enterprises.ucdavis.diskTable.dskEntry.diskAvail.1 = 316325
# enterprises.ucdavis.diskTable.dskEntry.diskUsed.1 = 437092
# enterprises.ucdavis.diskTable.dskEntry.diskPercent.1 = 58
# enterprises.ucdavis.diskTable.dskEntry.diskErrorFlag.1 = 0
# enterprises.ucdavis.diskTable.dskEntry.diskErrorMsg.1 = ""

# -----------------------------------------------------------------------------

Thank you.

Kind regards, Yann