Unmarshal Exception - Class not found

[Matt Bucknam]

Please help me with what the cause of this problem could be. If I put my data stub in the classpath of the client it works fine but if I try to set the server to download it, I get an exception.
Can anyone tell if this error is being thrown from the server or the client and how in the heck do I fix it???
This is the command line for the server:
C:\test>java -Djava.security.policy=policy
-Djava.rmi.server.codebase=file:/c:\
test\classes/ -classpath ./ suncertify.server.DataServer
DataServer.main: creating registry
DataServer.main: creating server
DataServer.main: binding server
This is the command line for the client along with the exception:
C:\temp>java -Djava.security.policy=policy -classpath c:\temp\ suncertify.gui.FlyApplication
Initializing
Looking up client
Remote Failure on method executionjava.rmi.UnmarshalException: error unmarshalli
ng return; nested exception is:
java.lang.ClassNotFoundException: suncertify.db.Data_Stub
java.rmi.UnmarshalException: error unmarshalling return; nested exception is:
java.lang.ClassNotFoundException: suncertify.db.Data_Stub
java.lang.ClassNotFoundException: suncertify.db.Data_Stub
at java.io.ObjectInputStream.inputObject(ObjectInputStream.java:981)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:369)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:232)
at sun.rmi.registry.RegistryImpl_Stub.lookup(Unknown Source)
at java.rmi.Naming.lookup(Naming.java:89)
at suncertify.client.DataClient.<init>(DataClient.java)
at suncertify.gui.FlyApplication.initialize(FlyApplication.java)
at suncertify.gui.FlyApplication.<init>(FlyApplication.java)
at suncertify.gui.FlyApplication.main(FlyApplication.java)