Applied Phlebotinum often works in ways that seem like they should be impossible. Occasionally, however, it really is impossible. The phlebotinum doesn't actually work in the way it's supposed to; instead, the psychic or reality-warping powers of its creator make it act as they intended. This may be an unconscious effect; in this case, the creator will think they really are a genius inventor. It may be conscious, and that's just how their powers work. Either way, they're limited to what they think will work, or what should work -- even if it wouldn't actually work once physics had its say.