Ok , So 've tried in many ways (forname,getinstance...) but I can't
create an instance and run this very simple thread class...
Now I'll post my code...

Server class :

//is very simple...
AgentClassLoader loader = new AgentClassLoader();//creates instance
of my redefinied classloader

//Load the main class through agentclassloader

Class class=loader.loadClass(AGENT_NAME,FILE_PATH,false);

//I won't post my classloader code because it works correctly

System.out.println("Now Launching Agent..");
try {

    class = Class.forName("app.MyTestAgent", true,loader);//I tryied
these methods..for name and new instance....but without success

//Note : "app" is the package and MyTestAgent is the class I want to
instanciate

      class.newInstance();

            } catch (Exception e) {
                e.printStackTrace();
                System.exit(1);
            }

2nd Class : "MyTestAgent" extend Thread and is veeery simple!!

public class MyTestAgent extends Thread {

Platform platform;//this is a simple collector class with only simple
data inside
public MyTestAgent (Platform platform) {
        this.platform = platform;
}
public void run(){//I have to run this method!!

//I won't post this code because is very simple
(retrieves parameters from plaform object)

}

Anybody knows how to do it??
Please Help Me!!
Thanks a lot guys ... bye..