This week's giveaway is in the EJB and other Java EE Technologies forum. We're giving away four copies of EJB 3 in Action and have Debu Panda, Reza Rahman, Ryan Cuprak, and Michael Remijan on-line! See this thread for details.
Does it work when you comment out the call to sort, and does the call to sort work if you run the same code from the console? Do you know the exact line in your code that calls the non-succesful sort? Is there anything on that line that possible could be null? Well... I don't have the code, so I am trying to make you debug it and solve it yourself. ;-)