由于未捕获的异常'NSInvalidArgumentException'而终止应用程序，原因：'在实体NSSQLEntity中找不到keypath parentDetail id = 2

I have one to many relation between two Entities, and when user select parent entity then i am showing subcategories using NSFetchedResultsController. and my fetching code is given below. By seeing the error it seems to the problem is while entring data. So i had attached the dummy insertion code too.I have one to many relation between two Entitie