#94 Error unloading Engine

[Angelo Conrado Loula]

I'm trying to use the SNTool Externally. I made a small
program to test it. It works fine except for unloading
the engine, I get the following error:

ontool.engine.EngineException: class loader not defined.
at
ontool.engine.EngineFactory.releaseClassLoader(EngineFactory.java:72)
at ontool.engine.Engine.run(Engine.java:577)

I created a sub class of the EngineFacade class. I
start it like this:
System.setProperty("profile","prod");
m=new mySNet("AdderNet");
m.setClasspath("path to my network package");
(...)
m.load();
(...)
m.step();
(...)
m.unload();

Am I missing some other configuration?