You should be trying to pin on the upper outer part of your glutes. The middle is the fattest part. You are trying to hit muscle, not fat, and the needle tip isnt that long. You really should do your leaner body parts until you lose some arse lard. Its also not uncommon to feel dizzy or even nauseous after pinning correctly the first few times. If you feel nothing, Im not so sure you nailed it, so to speak.