Monitor conversation

trixbox Version: 1.1.0
FreePBX 2.1.1

I am newbie to Asterisk.
I want to enable recording for a few extensions which are member of queue by using web management interface freepbx.

Even i define the type of recording wav for the queue and can see the wav files created under /car/spool/asterisk/monitor the file sizes almost same(approximatley 600b) and nothing recorded

Is there any suggestion.

Thanks

Taylan KIRAN