This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
Joey It means that whatever it is you're trying to do isn't supported by whatever you're trying to do it to. What are you doing when it happens? Try to catch it and then print the stack trace and the message from the exception. If that doesn't help you out, post the results here and we'll give it a shot.