Can you do pinch harmonics on any p?

I have a schecter hellraiser standard and a cheap little walmart amp and I can't do harmonics on it and I was wondering if you need a better amp ( well I need a better one any way cuz walmart sucks) but I dnt have the money yet and also wondering if it's just me and my technique I know you have to hit it at milliseconds after you pluck the string with tje side part of your thumb and all but it doesn't work for me