this is my diagram

and this is my method to add food and its category .
food add to database correctly , but it does not add to foodcategorySelected table

        public async Task AddFoodCategoryToFoodList(int foodId, List<int> foodCategoryId)
    {
        if (!foodCategoryId.Any()) return;
        foreach (var foodCat in foodCategoryId)
        {
            FoodSelectedCategory foodSelectedCategory = new FoodSelectedCategory()
            {
                FoodId = foodId,
                FoodCategoryId = foodCat,
                RegisterDate = DateTime.Now,
                

            };
            await _foodRepository.AddFoodCategoryToFood(foodSelectedCategory);
            await _foodRepository.SaveChanges();
        }

    }

before that I have a method to get information with food and selected category :
Food adds to database and when goes to this method, how ever it takes all Ids (food and food categories) but can not add and have this error:

my main method:

   public async Task<CreateFoodResult> CreateFoodByAdmin(CreateFoodViewModel createFoodViewModel) { Food food = new Food()
 {
     FoodTitle = createFoodViewModel.FoodTitle.SanitizeText(),
     IsActive = createFoodViewModel.IsActive,
     RegisterDate = DateTime.Now,
     FoodDescription = createFoodViewModel.FoodDescription.SanitizeText(),
     IsDelete = true,
     CreatedUser = createFoodViewModel.CreatedUser,
 };

 if (createFoodViewModel.FoodAvatar != null)
 {
     string imageName = NameGenerator.GenerateUniqCode() +
                        Path.GetExtension(createFoodViewModel.FoodAvatar.FileName);
     createFoodViewModel.FoodAvatar.AddImageToServer(imageName, FilePath.FilePath.FoodAvatarServer, 100,
         100, FilePath.FilePath.FoodAvatarThumbServer);
     food.ImageFood = imageName;

 }

 await _foodRepository.CreateFoodByAdmin(food);
 await _foodRepository.SaveChanges();

 if (createFoodViewModel.SelectedFoodCategory != null)
 {
     await AddFoodCategoryToFoodList(food.FoodId, createFoodViewModel.SelectedFoodCategory);
     await _foodRepository.SaveChanges();
 }

 return CreateFoodResult.Success;

}

and I see this error:

SqlException: The INSERT statement conflicted with the FOREIGN KEY constraint "FK_FoodSelectedCategories_FoodCategories_FoodCategoryId". The conflict occurred in database "EvSef_db", table "dbo.FoodCategories", column 'FoodCategoryId'.