NameNotFoundException make me crazy

Hi
I use OC4J 903 and Jbuilder 8 with oc4j plugin to start a project.
At the begining, I write a very simple stateless session bean called HelloWorld which is its jndi name and create another client to call HelloWorld bean, but when I run the client to call session bean, it throws NameNotFoundException to tell me HelloWorld is not found. That is a quite a simple test and I am pretty sure everything in the package like ejb-jar.xml orion-ejb.xml etc.
Can anyone guide me what is the problem?
I test this simple app on my XP machine with OC4J based on JDK1.4.
My ear file is named info_eai.ear and my context env is
env.put(Context.INITIAL_CONTEXT_FACTORY,"com.evermind.server.rmi.RMIInitialContextFactory");
env.put(Context.SECURITY_PRINCIPAL,"admin");
env.put(Context.SECURITY_CREDENTIALS,"123456");
env.put(Context.PROVIDER_URL, "ormi://localhost:23791/info_eai");
then I look up "HelloWorld" which is a jndi name, but fail again.
I notice no matter what version oracle 9i AS is , it doesn't have announced to support windows xp which is the os I am using now. I wonder whether windows xp cause the jndi lookup failuare(NameNotFoundException)?
I just do a quite simple hello world ejb which I played on weblogic/jboss tons of times without any problems, but sucks at oracle. Can anyone help me out ?
Thanks