JMF Receiving media by RTP

I'm working on program for transmitting and receiving audio through RTP in local machine, but the program doesn't receive the data. It never goes into update(ReceiveStreamEvent event).  The following is the portion of the code. is there any problem? Thx a lot

public class ReceiveMeida  implements ReceiveStreamListener, ControllerListener  {
public ReceiveMeida() {
      RTPManager rtpManager;
      SessionAddress localAddr;
      int port = 5000;
      
      try {
            localAddr = new SessionAddress(InetAddress.getLocalHost(),port);
            rtpManager = RTPManager.newInstance();
            rtpManager.initialize(localAddr);
            
            rtpManager.addReceiveStreamListener(this);
            
            
      }
      catch (Exception  e) {
      }
}


public void update(ReceiveStreamEvent event) {
               
        if (event instanceof NewReceiveStreamEvent) {
             Player newplayer;
             
             try {
                 ReceiveStream receiveStream = event.getReceiveStream();
                 DataSource dsource = receiveStream.getDataSource();
                 
                 newplayer = Manager.createPlayer(dsource);

             }
             catch (Exception e) {
             }
 
             if (newplayer == null) return;
 

             newplayer.addControllerListener(this);
             newplayer.realize();
           
             

         }
         
}
public synchronized void controllerUpdate (ControllerEvent e) {
           if (e instanceof RealizeCompleteEvent) {
                 newplayer.start();
           }
}
}