you're doing it in the wrong place weijia. when you move your left hand up the fret, you're supposed to move up the spot where you pick , too. all harmonics are basically the same distance apart from eachother. artificial harmonics are like recreated natural harmonics, when you think about. like try this, do a natural harmonic on the 12th fret. now do a artificial harmonic with the left hand fingering the 1st fret and the right hand picking where the 13th fret is on the bridge. it should sound similar to the natural harmonic you played, only it's transposed half a step.

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