Yeah I never figured out the difference between pinch harmonics and artifical harmonics. It doesn't really matter to me though, but you can get a wicked scream sound by playing harmonics as chords, like this:

e:---A.H------
b:---8-----
g:---7-----
d:---5-----
a:---------
e:---------

You just play this chord as you would regularly but as artifical (pinch) harmonics. Try different chords to get different screams. Works really good if your into metal type stuff. Even try adding alittle vibrato or bend to get that squeel effect.

It's kind of a hard technique to master, but it's a bigger screamer than just single note artificial harmonics. Plus you can play them anywhere on the fretboard. The effect you got was probably like chris said.