error in subscribing topic

[czy11421]

I am running ActiveMQ 5, in the admin web page, I could see 
"STOCKS.SUNW" in Topics, and this topic is sending out message, then how 
could I subscribe this topic and get the published message ?

I have tried this coding, but I get the error as bottom. Where is the bug ?
Thanks.

//////////////////////// code /////////////////
Properties props = new Properties();
            props.setProperty(Context.INITIAL_CONTEXT_FACTORY, 
"org.apache.activemq.jndi.ActiveMQInitialContextFactory");
            props.setProperty(Context.PROVIDER_URL, 
"tcp://localhost:61616");
            javax.naming.Context ctx = new InitialContext(props);
            // lookup the connection factory
      javax.jms.TopicConnectionFactory factory = 
(javax.jms.TopicConnectionFactory) ctx.lookup("ConnectionFactory");
            // create a new TopicConnection for pub/sub messaging
      javax.jms.TopicConnection conn = 
factory.createTopicConnection();  //getTopicConnection();
            System.out.println(conn); // output this : 
ActiveMQConnection 
{id=ID:xxxx-PC-51013-1252720683131-0:0,clientId=null,started=false}     
            // lookup an existing topic
      javax.jms.Topic mytopic = (javax.jms.Topic) 
ctx.lookup("STOCKS.SUNW"); //error is from here
            // create a new TopicSession for the client
      javax.jms.TopicSession session = conn.createTopicSession(false, 
TopicSession.AUTO_ACKNOWLEDGE);
            // create a new subscriber to receive messages
      javax.jms.TopicSubscriber subscriber = 
session.createSubscriber(mytopic);
      System.out.println(subscriber.receive());

////////////////////////// Exception ///////////////////
Exception in thread "main" javax.naming.NameNotFoundException: STOCKS.SUNW
  at 
org.apache.activemq.jndi.ReadOnlyContext.lookup(ReadOnlyContext.java:225)
  at javax.naming.InitialContext.lookup(Unknown Source)
  at com.Test.main(Test.java:31)