receive after sending (rtpduphello)

Hi.

I have a problem.
The simple code:
	// simplified
	rtp_session->putData(...)
	while(true){
		adu = rtp_session->getData(...)
	}
does not work. The program does not send anything out. When I delete the while 
loop, the data is send.

Also the compiled demo from source "rtpduphello" only prints out 
<This is rtpduphello, a very simple test program for ccRTP.
<Strike [Enter] when you are fed up.
<localhost is going to talk to perself through 127.0.0.1...
<The queue A is active.
<The queue B is active.
<Transmitting...
<A: sending message at 14:40:55...
<B: sending message at 14:40:55...
<A: sending message at 14:40:57...
<B: sending message at 14:40:57...
<A: sending message at 14:40:59...
<B: sending message at 14:40:59...
and nothing gets received. Also tcpdump does not get anything from 
rtpduphello.

Help please.
THANKS