When I tried to compile simple typesafe\' akka program (scala 2.10, akka, 2.1.0):
scalac -cp \"akka-actor_2.10-2.1.0.jar:akka-camel_2.10-2.1.0.jar\" write2.
To me it was JDK not set on PATH neither JAVA_HOME
You can add JAVA_HOME to point to your JDK root folder and add jdk/bin folder (wich inludes javac) directly to the path.
You can refer to the Oracle docs for instruccions on how to add the path http://docs.oracle.com/javase/7/docs/webnotes/install/windows/jdk-installation-windows.html