i am trying to implement peasycam into my sketch and i don't know why.

1. FATAL EXCEPTION: GLThread 10
2. java.lang.NoClassDefFoundError: peasy.PeasyCam$PeasyMousewheelListener
3.     at peasy.PeasyCam.<init>(Unknown Source)
4.     at peasy.PeasyCam.<init>(Unknown Source)
5.     at processing.android.test.atomos.Atomos.setup(Atomos.java:31)
6.     at processing.core.PApplet.handleDraw(PApplet.java:1783)
7.     at processing.core.PGraphicsAndroid3D$A3DRenderer.onDrawFrame(PGraphicsAndroid3D.java:7358)
8.     at android.opengl.GLSurfaceView$GLThread.guardedRun(GLSurfaceView.java:1363)
9.     at android.opengl.GLSurfaceView$GLThread.run(GLSurfaceView.java:1118)

i have a simple implementation of PeasyCam as seen below:

import peasy.org.apache.commons.math.*;
import peasy.*;
import peasy.org.apache.commons.math.geometry.*;

1. PeasyCam cam;
2. void setup() {
3.   cam = new PeasyCam(this, 200);
4.   cam.setMinimumDistance(-500);
5.   cam.setMaximumDistance(500);
6. }
7. void draw() {
8.   smooth();
9.   background(255);
10. }
11. public boolean surfaceTouchEvent(MotionEvent event) {
12.   float initialDist = 0;
13.   float currentDist = 0;
14.   switch(event.getAction()) {
15.   case MotionEvent.ACTION_DOWN:
16.     initialDist = dist(event.getX(0), event.getY(0), event.getX(1), event.getY(1));
17.     break;
18.   case MotionEvent.ACTION_MOVE:
19.     currentDist = calculateZoom(event);
20.     cam.setDistance(cam.getDistance()*(currentDist/initialDist));
21.     break;
22.   case MotionEvent.ACTION_UP:
23.     break; 
24.   default:
25.     break;
26.   }
27.   return super.surfaceTouchEvent(event);
28. }

1. public float calculateZoom(MotionEvent event){
2.   float zoom = 1;
3.   if(event.getPointerCount() == 2){
4.     zoom = dist(event.getX(0), event.getY(0), event.getX(1), event.getY(1));
5.   }
6.   return zoom;
7. }

any help would be greatly appreciated.