cosnaming/nameservicepackage not found

[QkrspCmptPop]

I am using org.omg.CosNaming.* to run client/server on two PC(XP) within a LAN. Actually, it is a sample project from one book, the name of the project is called CorbaJavaBook. The server provides a count method and the client is supposed to invoke the method either locally or remotely. And the sequence of start up is runnameserver, run server and client. They run very well in the same machine. And I test running remotely as follows:

1. making sure each machine can ping each other successfully
2. start up nameserver successfully on each machine
3. start up the server on one machine
4. start up the client on another machine

usually, it generates two erros
1. cosnaming/nameservicepackage not found:1.0
2.CORBA.COMM_FAILURE minor code 201

The project just uses nameservice in a normal way:
Server: get a reference of NameService; bind the object to nameservice
Client: get a reference of Nameservice; resolve the object in nameservice

I attached the server client code with files.