Serializable Obj

[dolev826]

I have to pass a List of Students from server to client, the student class is implements Serializable, but I recieve :
java.rmi.UnmarshalException: error unmarshalling return; nested exception is:
java.io.WriteAbortedException: writing aborted; java.io.NotSerializableException: java.lang.Object
Exceptions. I can't figure why this happens and how can I resolve it?