[j-nsp] SNMP v3 configurations

[snort bsd]

Hi all:

here is my configuration (for testing) for snmp v3:

v3 {
    usm {
        local-engine {
            user tester {
                authentication-sha {
                    authentication-key "xxxxxxx"; ## SECRET-DATA
                }
                privacy-none;
            }
        }
    }
    target-address test_1 {
        address 172.32.1.10;
        target-parameters test-lab;
    }
    target-address test_2 {
        address 172.32.1.11;
        target-parameters test-lab;
    }
    target-parameters test-lab {
        parameters {
            message-processing-model v3;
            security-model usm;
            security-level authentication;
            security-name lab;
        }
    }
    snmp-community lab {
        security-name lab;
        tag lab;
    }
}
engine-id {
    use-mac-address;
}
trap-group test {
    version all;
    categories {
        authentication;
        chassis;
        link;
        routing;
        sonet-alarms;
    }
}

but the tests were failed:

home at bn:~:$ snmpwalk -v 3 -u tester -l AuthNoPriv -a SHA -A test -m ALL 
172.32.1.10
Error in packet.
Reason: authorizationError (access denied to that object)


did I miss something in my configuration?

Thanks in advance