RMI COMPILING & SECURITY ERRORS

HAY I HAVE CREATED A SIMPLE CLIENT AND SERVER USING RMI,

EVERY THING IS COMPILED, but when i try to execute the server by assigning security privilages i get an error msg,

i.e

Remote Exception: java:.rmi.serverException: remoteException occured in serverthread;

nested exception is

java.rmi.UnmarshalException error unmarshalling arguments;

nested exception is

java.lang.classNotFoundException: SampleServerImpl_stup

i already checked that stup file is present in that folder, and i m using the command i.e

java -cp d:\java\RMI; -Djava.security.policy=policy.all SampleServerImpl

[643 byte] By [GegegegegeRisea] at [2007-11-27 11:06:49]