Sending RTCP packets

Hi,
How can i send RTCP packets from a receiver to a sender? My problem is that 
my sender sends automatically RTCP packets (SR when RTP packets were sent 
and RR when there were not RTP packets). But my Receiver doesn't send any 
RTCP packet to the sender.
I've used RTPListen, RTPSend, audiotx and audiorx.
If I want to see the number of lost packets from sender to Receiver, isn't 
this information in RTCP packets from Receiver? Or am i mistaken and that 
info can be consulted in RTCP packets from Sender to Receiver?
Anyway, how can i see the information in RTCP packets? (information like 
Cummulative packets lost, fraction lost,...)
Thanks a lot