Bug in SNMP-GET?

We receive wrong data when doing snmp-get on our equipment. The problem
seems to apply to Integer OID with negative values. See example using
nxsnmpget and Net-SNMP's snmpget:
the OID 8 is STRING value and OID 21 is equivalent integer value:

NetXMS:
./nxsnmpget -c public -v 2c 10.0.0.1 1.3.6.1.4.1.161.19.3.2.2.8.0
.1.3.6.1.4.1.161.19.3.2.2.8.0 [04]: -57 dBm
./nxsnmpget -c public -v 2c 10.0.0.1 1.3.6.1.4.1.161.19.3.2.2.21.0
.1.3.6.1.4.1.161.19.3.2.2.21.0 [02]: 198

Net-SNMP
snmpget -c public -v2c 10.0.0.1 1.3.6.1.4.1.161.19.3.2.2.21.0
WHISP-SM-MIB::radioDbmInt.0 = INTEGER: -57
snmpget -c public -v2c 10.0.0.1 1.3.6.1.4.1.161.19.3.2.2.8.0
WHISP-SM-MIB::radioDbm.0 = STRING: -57 dBm

I have a wireless accesspoint that we want statistics from. The data is
availible in an SNMP table. The challenging thing is that the number of
clients connected is dynamic. How do I configure a DCI collection to
collect data from a table?

The dump of a table could look like this:
Client Name / Mac-address / Signal Strength / Noise Ratio
client 1 / 00:00:00:00:00:a1 / -58 / 0
client 2 / 00:00:00:00:00:a2 / -64 / 0
client 3 / 00:00:00:00:00:a3 / -23 / 0
client 4 / 00:00:00:00:00:a4 / -50 / 0

Is it possible to to make NetXMS to send a snmpset before doing snmpget?

-- 
Christoffer Blindheim