error: The object cannot be deleted because it was not found in the ObjectStateManager.?

Question

Attempting to delete customer data I keep getting the same error "The object cannot be deleted because it was not found in the ObjectStateManager." Not familiar with this any help that can be offered is appreciated.

public string DeleteCustomer(ABSCRCustomer Customer)
    {
        string ret = "";

        using (CSRAAEntities db = new CSRAAEntities())
        {

            try
            {
                db.ABSCRCustomers.Remove(Customer);
                db.SaveChanges();
            }
            catch (Exception ex)
            {

                ret = "Error deleting Customer, Error: " + ex.Message;

            }

        }//using
        return ret;
    }//DeleteCustomer