First of all, provide some details, I'm using processing 1.5.1(required for school), Eclipse Indigo, and the appropriate version of ControlP5 for processing 1.5.1. I get the follow error when I try to run my project:

Exception in thread "Animation Thread" java.lang.NoSuchMethodError: processing.core.PApplet.registerMethod(Ljava/lang/String;Ljava/lang/Object;)V
    at controlP5.ControlWindow.init(Unknown Source)
    at controlP5.ControlWindow.<init>(Unknown Source)
    at controlP5.ControlP5.init(Unknown Source)
    at controlP5.ControlP5.<init>(Unknown Source)
    at controltest.ControlTest.setup(ControlTest.java:11)
    at processing.core.PApplet.handleDraw(Unknown Source)
    at processing.core.PApplet.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)

For code I have the following:

import processing.core.PApplet;
import controlP5.*;

@SuppressWarnings("serial")
public class ControlTest extends PApplet {
    public ControlP5 cp5;
    public void setup() {
        size(400,600);
        cp5 = new ControlP5(this);
    }

    public void draw() {

    }
   
    public static void main(String _args[]) {
        PApplet.main(new String[] { controltest.ControlTest.class.getName() });
    }
}

I have imported controlP5, although now it's in my referenced libraries twice for some reason. As you can see I don't have much. I can't figure out what's going on. Any help would be greatly appreciated.