You check mouseX at the end of draw(), you should do all your checks inside mousePressed().

Very minor remark: catched should be caught.

Minor remark: instead of:
if (x == true)
use
if (x)
and in place of
if (x == false)
use
if (!x)
This uses the booleans for what they are really (otherwise, a simple int variable with 0 or 1 in it can do the same job).

You better type your array list:
ArrayList<Pesa> pesas= new ArrayList<Pesa>();
Thus, no need for cast when getting the value:

for(int i = 0;i < pesas.size();i++){

          Pesa pesa = pesas.get(i);
or with the modern syntax:
for (Pesa pesa : pesas)
  // Replaces the two lines above
(if you don't need i)

Except perhaps the remark on mouseX, these advices won't fix anything but they can be useful in the future...
It is hard to run your code (we don't have the images), so it is hard to see where the problem can be.

I've already told him about the angle brackets to specify the content's data-type
inside a Collection to avoid cast operators to extract them in his previous post:
http://forum.processing.org/topic/arraylist-11-7-2013

Also, I've mentioned that a simple clear() method would be enough to remove all contents at once
from a List, rather than a backwards loop.

But I guess he hasn't picked up everything I've said. 

@ pacoruizg.. you can aways upload your images and use loadImage("some url"), so people can easily run your code to help you :)