Are you by chance using Java 8 to compile? I get the same error on my Linux machine with "javac 1.8.0_05", but everything works fine when using the old JDK 7. Already talked with Immortius about this on IRC. Is it possible for you to try it again with Java 7?
Got some more details like a log statement? And what did you do to compile?Now when I want to run my compiled version it gives a Lauch4j Error! How can I fix this