In a song I'm trying to learn, there's a pinch harmonic on the 15th fret of the G string, and I can't do it properly. I can play pinch harmonics up to the 13th fret without too much grief.

If I manage to get a pinch harmonic from it, it's very weak, and hardly even rings out.

I don't think it's my technique, as I can basically play Master Of Puppets using nothing but pinch harmonics.

Is it normal for a guitar to be incapable to do pinch harmonics on higher frets?
"I think, as a musician, you should practice your technique to be as good as you need to be to facilitate whatever ideas come into your head."
- Devin Townsend
probably just finding a sweet spot thing, work up to it - start at fret 12 (pinching at 24) and work your way up.

however, it might be something to do with pickup placement - if a coil/pole piece is placed under a node (a point of no oscillation in the string - therefore zero amplitude), the harmonic will not come through on the amp (which is why pinches come out softer or not at all with a neck pickup).
can you get the harmonic to come out at all when unplugged?