Java APIs

Hello all
im trying to connect to throw my name service without IOR but with
the host and port , ( by the way when I working with ior it is working fine )
I doing this simple example taken from sun's java site :

Properties props = new Properties();
props.put("org.omg.CORBA.ORBInitialPort", "12345");
props.put("org.omg.CORBA.ORBInitialHost", "localhost");
String[] newArgs = new String[0];
ORB orb = ORB.init(newArgs,props);
org.omg.CORBA.Object obj = orb.resolve_initial_references("NameService");


but im getting error saying :
org.omg.CORBA.ORBPackage.InvalidName: IDL:omg.org/CORBA/ORB/InvalidName:1.0
at org.jacorb.orb.ORB.resolve_initial_references(ORB.java:1231)

using jac orb as client orb and visibroker as server orb