No they are not pointing to same .class/.jar files. Is that a requirement? If so, how would the .Net client support PDXSerialization?
Also, other domain classes point to different .class/.jar locations on client than that of server and there doesn't seem to be a problem with them.
As I pointed earlier, could it be that this class "UserActivation" is used inside of a request object and also inside of a response object, be the source of problem?