Invokerepeating and itween problems

hello Im making a script with itween here is the script:
using UnityEngine;
using System.Collections;

public class RotateBy : MonoBehaviour {
	public float snelheid = 2F;
	public AudioClip geluid;

	void Start () {
		audio.clip = geluid;

		audio.loop = true;
		audio.Play ();
	iTween.RotateBy (gameObject,iTween.Hash (

			"x", 2,
			"speed", snelheid

	void Example () {
		InvokeRepeating ("Faster", 2, 0.3F);


I want The InvokeReating thing on the “snelheid” thing In rule 17 I want that the object with this script goes faster and faster but fail. can anyone help me?

Rather than use iTween, just do this in Update() to rotate:

 transform.Rotate(Time.deltaTime * speed, 0,0);

‘speed’ is a variable you declare at the top of the file. Then in your Faster function, increase the value of ‘speed’.