ReflectiveOperationException class definition not found

[mohnishkodnani]

I am trying to use the monitor in my akka project.
I have aspectjweaver 1.7.4 and when I run the application, I get
Exception in thread "main" java.lang.NoClassDefFoundError: java/lang/ReflectiveOperationException
at akka.dispatch.Dispatcher.registerForExecution(Dispatcher.scala:118)
at akka.dispatch.MessageDispatcher.attach(AbstractDispatcher.scala:133)
at akka.actor.dungeon.Dispatch$class.start(Dispatch.scala:87)
at akka.actor.ActorCell.start(ActorCell.scala:369)
at akka.actor.LocalActorRef.start(ActorRef.scala:321)

I am using JDK 1.6
/usr/lib/jvm/java-6-oracle/bin/java

Is JDK 7 a requirement to use this project ?