Time to talk about the exceptional factors I refer to in my post on Astrology & Tarot; specifically, #4 in which I state that a personal/ specific reason can be a reason for a failed magickal working.
There are people that have a natural immunity to spiritual forces, which makes it hard to influent or target them. I unfortunately have had to deal with this for personal goals as well as ventures for customers; the person either has a resilient mind, is exceptionally strong mentally or has some other astral barrier which makes it so hard to influence him/ her. The benefit is obvious, drawback for these people is that they will never progress beyond their current level (mentally or astrally) and they’re not even aware that they possess this trait, more often than not.
Targeting someone like that will either work with tremendous difficulty and we’ll have to throw pretty much everything we have at them in the way of resources, or decide that it’s not worth it overall and move on.
Last but not least, it must be pointed out too that the adverse is also the case- people that are extra susceptible to mentioned forces. The same can be said of physical ailments.