Getting NotBoundException while writing a Java RMI chat application :-/

I have written a Java RMI chat application. There are four classes and two interfaces. Here they are:

ChatClient

import java.rmi.RemoteException;
import java.rmi.server.UnicastRemoteObject;
import java.util.Scanner;
com.za.tutorial.rmi.server.ChatServerIF;

public class ChatClient extends UnicastRemoteObject implements ChatClientIF,Runnable {
private ChatServerIF chatServer;
private String name = null;

protected ChatClient(String name, ChatServerIF chatServer) throws RemoteException {
    this.name = name;
    this.chatServer = chatServer;
    chatServer.registerChatClient(this);
}

public void retrieveMessage(String message) throws RemoteException {
    // TODO Auto-generated method stub
    System.out.println(message);
}

public void run() {
    Scanner scanner = new Scanner(System.in);
    String message;
    while(true){
        message = scanner.nextLine();
        try {
            chatServer.broadcastMessage(name + " : " + message);
        } catch (RemoteException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    }

}

ChatClientDriver

import java.net.MalformedURLException;
import java.rmi.Naming;
import java.rmi.NotBoundException;
import java.rmi.RemoteException;
import com.za.tutorial.rmi.server.ChatServerIF;

public class ChatClientDriver {
public static void main(String[] args) throws MalformedURLException, RemoteException, NotBoundException {

String chatServerURL = "rmi://localhost/RMIChatServer";
ChatServerIF chatServer = (ChatServerIF) Naming.lookup(chatServerURL);
new Thread(new ChatClient(args[0],chatServer)).start();
}
}

ChatClientInterface

import java.rmi.Remote;
import java.rmi.RemoteException;

public interface ChatClientIF extends Remote {
void retrieveMessage(String message) throws RemoteException;
}

ChatServer

import java.rmi.RemoteException;
import java.rmi.server.UnicastRemoteObject;
import java.util.ArrayList;
import com.za.tutorial.rmi.client.ChatClientIF;

public class ChatServer extends UnicastRemoteObject implements ChatServerIF {


private ArrayList<ChatClientIF> chatClients;
protected ChatServer() throws RemoteException {
    chatClients = new ArrayList<ChatClientIF>();
    }

public synchronized void registerChatClient(ChatClientIF chatClient)
        throws RemoteException {
    this.chatClients.add(chatClient);
}

public synchronized void broadcastMessage(String message) throws RemoteException {
    int i = 0;
    while(i < chatClients.size()){
        chatClients.get(i++).retrieveMessage(message);
    }
}
}

ChatServerDriver

import java.net.MalformedURLException;
import java.rmi.Naming;
import java.rmi.RemoteException;

public class ChatServerDriver {

public static void main(String[] args) throws RemoteException, MalformedURLException {
Naming.rebind("RMIChatServer", new ChatServer());
}
}

ChatServerInterface

import java.rmi.Remote;
import java.rmi.RemoteException;
import com.za.tutorial.rmi.client.ChatClientIF;

public interface ChatServerIF extends Remote {
void registerChatClient(ChatClientIF chatClient) throws RemoteException;
void broadcastMessage(String message) throws RemoteException;
}

When I run it on Commando, first of all I run rmic ChatClient and ChatServer, then rmiregistry. Then i run chatServerDriver which works completely fine. after that, when I run chatClientDriver with a name, I get the following error, I dont understand why :/ Can I get any solution for this?

Thanks :)

Exception in thread "main" java.rmi.NotBoundException: RMIChatServer
    at sun.rmi.registry.RegistryImpl.lookup(RegistryImpl.java:136)
    at sun.rmi.registry.RegistryImpl_Skel.dispatch(Unknown Source)
    at sun.rmi.server.UnicastServerRef.oldDispatch(UnicastServerRef.java:409)
    at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:267)
    at sun.rmi.transport.Transport$1.run(Transport.java:177)
    at sun.rmi.transport.Transport$1.run(Transport.java:174)
    at java.security.AccessController.doPrivileged(Native Method)
    at sun.rmi.transport.Transport.serviceCall(Transport.java:173)
    at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:553)
    at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:808)
    at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:667)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
    at java.lang.Thread.run(Thread.java:722)
    at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(Unknown Source)
    at sun.rmi.transport.StreamRemoteCall.executeCall(Unknown Source)
    at sun.rmi.server.UnicastRef.invoke(Unknown Source)
    at sun.rmi.registry.RegistryImpl_Stub.lookup(Unknown Source)
    at java.rmi.Naming.lookup(Unknown Source)
    at com.za.tutorial.rmi.client.ChatClientDriver.main(ChatClientDriver.java:15)