mvc update creating not updatng in entityframework

Question

IM using c# and MVC and the entity framework, now i have an entity that i am passing through to the model of the view for an update, my edit post back takes back the entity and a few extra fields that i am using editors for. i have a repository manager and it has a entity context, however when i call savechanges on my repository base (shown below) it seems to be adding a new entity as opposed to updating the one that is coming through. and i have no idea why??

public void SaveChanges()
    {
        TransactionOptions options = new TransactionOptions()
        {
            IsolationLevel = System.Transactions.IsolationLevel.ReadCommitted
        };
        using (TransactionScope scope = new TransactionScope(TransactionScopeOption.RequiresNew, options))
        {
            try
            {
                RepositoryManager.GetContext(GetContextType()).SaveChanges();
                scope.Complete();
            }

            catch
            {
                scope.Dispose();
                throw;
            }
        }
    }

CORRECTION IT SEEMS TO BE UPDATING AND CREATING A NEW ONE

im doing the following in my controller

public ActionResult Edit(FlightInstance flight, string timeselector, string dateselector, int destinationlocation, int departurelocation) { try { flight.TimeOfFlight = DateTime.Parse(dateselector + " " + timeselector); flight.DestinationLocation = m_LocationRepository.GetLocation(destinationlocation); flight.DepartureLocation = m_LocationRepository.GetLocation(departurelocation); if (flight.IsValid) { m_FlightRepository.UpdateFlightInstance(flight); return View("List"); }

and ive resorted to the following to try and get it to update the object in

public void UpdateFlightInstance(FlightInstance flight) {
var flights = (from flightInDb in Context.FlightInstance .Include("DestinationLocation") .Include("DepartureLocation") where flightInDb.ID == flight.ID select flightInDb).FirstOrDefault();

        if (flights != null)
        {
            flights.Name = flight.Name;
            flights.ID = flight.ID;
            flights.EntityKey = flight.EntityKey;
            flights.TimeOfFlight = flight.TimeOfFlight;
            flights.Description = flight.Description;
            flights.TimeOfFlight = flight.TimeOfFlight;
            flights.DestinationLocation = flight.DestinationLocation;
            flights.DepartureLocation = flight.DepartureLocation;

        }

        SaveChanges();
    }