How do you do Pinch Harmonics on all guitars?

i tried a ibanez rg350dx at a music store and i wasn't able to do pinch harmonics on it. i had a heavey sound on the amp yet i guess i just couldn't find the spot on the guitar to make it scream. I saw videos on youtube of people doing harmonics really well though. Any thoughts or suggestions? btw i am never able to do pinch harmonics on guitars that have a middle pick up. Just never works