multithreading monitoring snmp

[palmis]

I have my application that make monitoring of subsystem by means of
snmp protocol.
Now it functions correctly if I select one subsystem at once. If I try
to select another subsystem to monitor, while there is the monitoring
in course, it stop the first ant start the most recent selected.
Why?

I have try to work with thread but I'm new with it.
Can you help me?

thaks
Palmis