I was learning how to play natural harmonics on the guitar. However, I've noticed that on my axe, a Peavey Predator, it only has five places were I get a good harmonic -- 5th, 7th, 12th, 19th frets and one just over the magnetic parts of the neck pick up. Is this unusual? I was under the impression that you could generally get harmonics from a number of different places on the guitar. Or are all guitars different, either individually, or by company and model?