Thumbed Harmonics

I have been trying to get the thumbed harmonics where you mute the string with oyur thumb and make it sound totally groovy. I kinda know what to do but i cant get ti to sound right, whats the problem man, can you help me out. And dont say its EQ because my freind made it work on my EQ too.

Try here, this helped me.

http://www.guitartricks.com/2000/trick.php?trick_id=4227&s_id=35

I have tried using that to help me, but the only place I can do it is on the 10th fret on the 2nd string with wah on full. I can't do it at all otherwise. Do you pinch the string hard or gently?