StackOverflowException serializes .netTiers object

I have a simple WCF service:

public Order[] GetOrdersByStatus(int statusid)
{
    OrderService os = new OrderService();
    TList<Order> orders = os.GetByOrderStateID(statusid);

    return orders.ToArray();
}

      

        
        
        
      

    

when it returns it, it throws a StackOverflowException in mscorlib. Any idea what could be causing this?

OrderService is a service created by NetTiers and Order is a NetTiers object. when i return the data, already pulled from the database and ready to go. What other than an error in WCF can throw a StackOverflowException after I return from my operation?