This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
The server JVM has a different version of class " jisp.base.RateGroupInfo" than the client. You have to sync the class definitions both at the server side and client. Mostly, people specify the serialVersionUID field in the serializable classes to avoid this problem.