I am guessing this error refers to rotateCube not being called properly??? I read other people who got this error and checked my curly brackets and such but nothing...what does this error mean exactly?

1. /* 3D Cube movement with arrow keys
2. When user hits LEFT the cube rotates left till user hits
3. right then it rotates right etc*/
4. 
   
5. import processing.opengl.*;
6. char currentKey = 'n';
7. 
   
8. void setup() {
9.   size(400, 400, P3D);
10. }
11. void draw() {
12.   if(keyPressed && key == CODED) {
13.     if(keyCode == UP) {
14.       currentKey = 'u';
15.     }
16.     if(keyCode == DOWN) {
17.       currentKey = 'd';
18.     }
19.     if(keyCode == LEFT) {
20.       currentKey = 'l';
21.     }
22.     if(keyCode == RIGHT) {
23.       currentKey = 'r';
24.     }
25.   }
26.   else {
27.     rotateCube(currentKey);
28.   }
29. }
30. rotateCube (char currentKey) {
31.   i+=.05;
32.   if(i == 2*PI) { i = 0; }
33.   if(currentKey == u) {
34.     rotateX(i);
35.   }
36.   if(currentKey == d) {
37.     rotateX(-i);
38.   }
39.   if(currentKey == r) {
40.     rotateY(i);
41.   }
42.   if(currentKey == l) {
43.     rotateY(-i);
44.   }
45. }