/*Same interface i have in my server computer.*/
package remoto;
import java.rmi.Remote;
import java.rmi.RemoteException;

public interface Mensageiro extends Remote {
    void enviarMensagem(String msg) throws RemoteException;
    String lerMensagem() throws RemoteException;
}
/**********************************************************************************************/
import remoto.*;
import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;
import java.rmi.RemoteException;
import java.rmi.NotBoundException;
public class MensageiroCliente {

    public static void main(String[] args) {
        try {
            Registry registry = LocateRegistry.getRegistry("192.168.1.102");
            Mensageiro m = (Mensageiro) registry.lookup("MensageiroServer");
            String resposta = m.lerMensagem();
            System.out.println("Resposta do Server: " + resposta);
        }  catch (RemoteException e) {
            System.out.println();
            System.out.println("RemoteException: " + e.toString());
        } catch (NotBoundException e) {
            System.out.println();
            System.out.println("NotBoundException: " + e.toString());
        } catch (Exception e) {
            System.out.println();
            System.out.println("Exception: " + e.toString());
        }
    }
}
/**********************************************************************************************/
Error1: 
NotBoundException: java.rmi.NotBoundException: MensageiroServer
/**********************************************************************************************/
Error2: Changing a little bit the string of LocateRegistry.getRegistry and adding the port "192.168.1.102:1099"

RemoteException: java.rmi.UnknownHostException: Unknown host: 192.168.1.102:1099; nested exception is: 
        java.net.UnknownHostException: 192.168.1.102:1099
/**********************************************************************************************/
I'm using Mint, with NetBeans 6.9 and typing java -version in terminal it appears:
java version "1.6.0_20"
OpenJDK Runtime Environment (IcedTea6 1.9.13) (6b20-1.9.13-0ubuntu1~10.10.1)
OpenJDK Client VM (build 19.0-b09, mixed mode, sharing)