After I run my server and rmiregistry successfully,when I try to run the client program with the following command (java -Djava.security.policy==client.policyechormiclient.Main) it throws the following remote exception

May 13, 2010 3:43:16 PM echormiclient.Main main

SEVERE: null

java.rmi.UnmarshalException: error unmarshalling return;
nested exception is:

java.lang.ClassNotFoundException: echormi.Calculate

at sun.rmi.registry.RegistryImpl_Stub.lookup
(Unknown Source)

at java.rmi.Naming.lookup(Unknown Source)

at echormiclient.Main.main(Main.java:36)

Caused by: java.lang.ClassNotFoundException: echormi.Calculate

at java.net.URLClassLoader$1.run(Unknown Source)

at java.security.AccessController.doPrivileged(Native Method)

at java.net.URLClassLoader.findClass(Unknown Source)

at java.lang.ClassLoader.loadClass(Unknown Source)

at java.lang.ClassLoader.loadClass(Unknown Source)

at java.lang.ClassLoader.loadClassInternal(Unknown Source)

at java.lang.Class.forName0(Native Method)

at java.lang.Class.forName(Unknown Source)

at sun.rmi.server.LoaderHandler.loadProxyInterfaces(Unknown Source)

at sun.rmi.server.LoaderHandler.loadProxyClass(Unknown Source)

at sun.rmi.server.LoaderHandler.loadProxyClass(Unknown Source)

at java.rmi.server.RMIClassLoader$2.loadProxyClass(Unknown Source)

at java.rmi.server.RMIClassLoader.loadProxyClass(Unknown Source)

at sun.rmi.server.MarshalInputStream.resolveProxyClass(Unknown Source)

at java.io.ObjectInputStream.readProxyDesc(Unknown Source)

at java.io.ObjectInputStream.readClassDesc(Unknown Source)

at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)

at java.io.ObjectInputStream.readObject0(Unknown Source)

at java.io.ObjectInputStream.readObject(Unknown Source)

... 3 more