SNMP Change keys Issue

Hi All
I have been facing a problem with snmpusm for creation of a new user from an existing user through cloning during Key Change.
The Existing user has been created using Passphrase and I intend to create the new user with a Auth and Encryption Keys rather that passphrases.
The documentation of snmpusm suggests the usage of -Ck option for the same.However the flag "f" is not identified for the option -C when i tried this.

The Versions:
SNMP:Net-SNMP 5.1.4
Kernel Version(Unix):2.4.20

The Syntax of the command used:
snmpusm -u user -l authpriv -a SHA -A authpassphrase -x AES -X encrKey [OPTIONS] passwd -Ca -Ck authpassphrase New_AuthKey

This shows that the flag k is not recognized for -C option.

Kindly let me know if net-SNMP hs to be upgraded for this.
when I see the documentation for snmpusm the option -Ck is perfectly on.

Thanks in advance

-Anand