Again with multiple IEntityChangeTracker interface instances
===

I'm trying to use context as partially as possible because I want my software to be used by multiple users and I already had problems with contexts integration... so what I'm doing is calling the context like that:

    entityManager = new EntityManager();

    IEnumerable<customers_question_set> customersQuestionSets = 
    entityManager.GetTradersCustomersQuestionSets(trader.id).ToArray<customers_question_set>();

    entityManager = null;

This way, I believe, not only I'm closing everything with =null but also detaching the objects from the context by .ToArray<object>().

But now I'm trying to add new item to the database and I've met a problem. This are my actions:

    private void button1_Click(object sender, EventArgs e)
        {
            trader trader = new trader();
            trader.companies.Add(parent.GetCompany());
            trader.login = textBox1.Text;
            trader.password_hash = Hasher.ToSha256Hash(textBox2.Text);

            EntityManager entityManager = new EntityManager();
            entityManager.SaveTrader(trader);
            entityManager = null;

            this.RefreshLists();
        }

    public class EntityManager
    {

        private mentor11Entities Mentor11Entities = new mentor11Entities();

        private mentor11Entities GetMentor11()
        {
            return this.Mentor11Entities;
        }

        public void SaveTrader(trader trader)
        {
            GetMentor11().traders.AddObject(trader);
            GetMentor11().AcceptAllChanges();
            GetMentor11().SaveChanges();
        }

    [...]

    }

The error happens at GetMentor11().traders.AddObject(trader) - how to detach it if it's a new member I didn't even take from anywhere?
