Concurrent calls not working for per session mode in WCF

static void Main(string[] args)
    {
        Thread[] t = new Thread[10];
        NetTcpBinding myBinding = new NetTcpBinding();
        EndpointAddress myEndpoint = new EndpointAddress("net.tcp://localhost:8000/MyService");
        ChannelFactory<IService1> myChannelFactory = new ChannelFactory<IService1>(myBinding, myEndpoint);
        IService1 instance = myChannelFactory.CreateChannel();
        for (int i = 0; i < 10; i++)
        {
            t[i] = new Thread(new ThreadStart(delegate() 
            {
                instance.MyOperation1();
            }));
        }
        for (int i = 0; i < 10; i++)
        {
            t[i].Start();
        }          
    }