What's the possible reason for such Exception, when i invoke a method of EJB3.0 object

Thank you in advance.

javax.naming.CommunicationException [Root exception is java.lang.ClassNotFoundException: org.jboss.proxy.ejb.EJBMetaDataImpl (no security manager: RMI class loader disabled)]
 at org.jnp.interfaces.NamingContext.lookup(NamingContext.java:713)
 at org.jnp.interfaces.NamingContext.lookup(NamingContext.java:572)
 at javax.naming.InitialContext.lookup(InitialContext.java:351)
 at com.paul.ejb3.Client.main(Client.java:16)
Caused by: java.lang.ClassNotFoundException: org.jboss.proxy.ejb.EJBMetaDataImpl (no security manager: RMI class loader disabled)
 at sun.rmi.server.LoaderHandler.loadClass(LoaderHandler.java:371)
 at sun.rmi.server.LoaderHandler.loadClass(LoaderHandler.java:165)
 at java.rmi.server.RMIClassLoader$2.loadClass(RMIClassLoader.java:620)
 at java.rmi.server.RMIClassLoader.loadClass(RMIClassLoader.java:247)
 at sun.rmi.server.MarshalInputStream.resolveClass(MarshalInputStream.java:197)
 at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1538)
 at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1460)
 at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1693)
 at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1299)
 at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1912)
 at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1836)
 at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1713)
 at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1299)
 at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1912)
 at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1836)
 at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1713)
 at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1299)
 at java.io.ObjectInputStream.readObject(ObjectInputStream.java:339)
 at java.rmi.MarshalledObject.get(MarshalledObject.java:135)
 at org.jnp.interfaces.MarshalledValuePair.get(MarshalledValuePair.java:57)
 at org.jnp.interfaces.NamingContext.lookup(NamingContext.java:637)
 ... 3 more