[Serusers] Not ANOTHER silly NAT question...

Well.. it probably is. I have had mixed success with SER 0.8.14 and RTPPROXY. I have RADIUS auth, accounting, MYSQL, blah, blah, blah, all working.... My question, however, surrounds NAThelper configuration. If I leave all clients behind NATs to attempt registration with private IPs, fix the IPs with NAThelper and proxy the streams, then everything works OK. If I inroduce a client that is on a LIVE IP address, I only get one-way audio to a natted client (the natted client can't hear the live client). I assume that what is happening is that the live client is attempting to send it's audio direct to the natted client, instead of via the proxy. I figure that I've missed something silly somewhere in the config, but I'm darned if I know where. I won't bother posting my entire config (unless specifically requested), rather I'd like a general pointer as to where I should be looking. Thanks in advance.