Confusing movieclips and buttons

Ok, I am getting really confused at this.
I have
A button ( one_btn ),
inside a movieclip ( two_MC)
inside another movieclip ( three_mc )
inside another movieclip ( four_mc )
inside my timeline.

When I click one_btn, I want it to gotoAndStop(32); in three_mc. I tried

_root.gotoAndStop(32);

, but that just does it on the main timeline, and I tried to put

 
  one_btn.onRelease = function(){ 
     three_mc.gotoAndStop(32); 
 } 
 

But that didn’t do anything.
Anyone know how to help?
Thank a lot.