Random Jump on the y axis

I Have an Enemy which moves on the x axis, I want it to jump on the Y axis randomly (Not every specific number of seconds)

I tried several ways with out success any suggestion...

Here is the code including the commented part

 var EvilGuy : Transform; 
 var jumpsound : AudioClip; 
 var spawnTime : float=1;
 var rangeDice : int = 5;

   function Start () {

   InvokeRepeating("MakeHimJump", 1, 5);

   //InvokeRepeating("Method", delayTime, repeatTime);  

    Debug.Log("Called"); }

    function MakeHimJump  () {
    var randomValue : int = Random.Range(1, rangeDice);     
    PlayAudioClip(jumpsound,
    transform.position, 1);
    transform.position.y+=1; 
}

Could you perhaps tell us if "Called" is being logged out correctly and how your EvilGuy does act? does the program compile and is there any movement?

Thanks.

edit: after more information:

 var EvilGuy : Transform; 
 var jumpsound : AudioClip; 
 var spawnTime : float=1;
 var rangeDice : int = 5;

   function Start () {

   //new: Moved random dice roll to the InvokeRepeating function. 
   InvokeRepeating("MakeHimJump", 1, Random.Range(1, rangeDice));

   //InvokeRepeating("Method", delayTime, repeatTime);  

    Debug.Log("Called"); }

    function MakeHimJump  () {   
        PlayAudioClip(jumpsound,
        transform.position, 1);
        transform.position.y+=1; 
}

I'm at work so I cannot test but try moving the random.range call like I have above.

Good luck