Error in writing a file with message while sending chat msg to client

Question

i want to store sending text in file every time while am sending msg to client as follows

private function send3():void
{
producer.send(message);
RmSrv.writetofile("poposdfasdfasdfsdf");
}

getting fault details follows... Channel.Security.Error error Error #2048 url: 'http://localhost:8400/messagebroker/amf'

if i comment RmSrv.writetofile("poposdfasdfasdfsdf");,it working ,but msg in not storing in a file...where i need to change & in which config file i need to write what ?