How to start a WCF hosted in a module? IAutoStart?

Hello,
I'm trying to host a WCF Service in a module. I need to call these statments when the application starts :

srv = new ServiceHost(typeof(VishnuService));
srv.Open();

I tried using IAutoStart interface and implements this:

        #region IAutoStart Membres

        ServiceHost srv;

        public void Start()
        {
            srv = new ServiceHost(typeof(VishnuService));
            srv.Open();

        }

        public void Stop()
        {
            srv.Close();
        }

        #endregion

But Starts method is never called...

An idea??
Thanks!