ArgumentOutOfRange AddEntity

        public PromotionLine AddProduct(Product product)
        {
            var promotionLine = new PromotionLine
                                    {
                                        PromotionId = PromotionId,
                                        PromotionLinkType = (byte)PromotionLinkType.Product,
                                        LinkId = product.ProductId
                                    };
            EntityManager.AddEntity(promotionLine);
            return promotionLine;
        }


Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: index

   at System.ThrowHelper.ThrowArgumentOutOfRangeException()
   at System.Collections.Generic.List`1.get_Item(Int32 index)
   at IdeaBlade.EntityModel.EntityKey.ConvertValues()
   at IdeaBlade.EntityModel.EntityGroup.FindEntityWrapper(EntityKey entityKey, Boolean includeDeleted)
   at IdeaBlade.EntityModel.EntityManager.FindEntityWrapper(EntityKey entityKey, Boolean includeDeleted)
   at IdeaBlade.EntityModel.ScalarEntityReference`1.FindToEntity()
   at IdeaBlade.EntityModel.ScalarEntityReference`1.FixupReferences()
   at IdeaBlade.EntityModel.EntityAspect.<FixupReferences>b__19(EntityReferenceBase eref)
   at IdeaBlade.Core.EnumerableFns.ForEach[T](IEnumerable`1 items, Action`1 action)
   at IdeaBlade.EntityModel.EntityAspect.FixupReferences()
   at IdeaBlade.EntityModel.EntityAspect.TrackChanged(EntityChangedEventArgs e)
   at IdeaBlade.EntityModel.EntityGroup.OnEntityChanged(EntityChangedEventArgs e)
   at IdeaBlade.EntityModel.EntityGroup.AddAttachedEntity(EntityAspect wrapper, EntityState entityState)
   at IdeaBlade.EntityModel.EntityManager.AttachEntityAspect(EntityAspect aspect, EntityState entityState)
   at IdeaBlade.EntityModel.EntityManager.AttachEntity(Object entity, EntityState entityState)
   at IdeaBlade.EntityModel.EntityManager.AddEntity(Object entity)

Even just doing this errors:

            var promotionLine = new PromotionLine();
            EntityManager.AddEntity(promotionLine);


This is the ctor:

        internal PromotionLine()
        {
            PromotionLineId = Guid.NewGuid();
        }

Any clues?

    var method = typeof(EntityKey).GetMethod("ConvertValues", BindingFlags.NonPublic | BindingFlags.Instance);
            method.Invoke(key, null);