itween: firing oncomplete AFTER ONE LOOP

have what i hope is a quick & easy question - i understand using oncomplete to hit a function (that does not loop), but what if i want to hit a function on the completion of one loop? is it possible?

     ht.Add("z",Random.Range(15.0F, 40.0F));
     ht.Add("time",Random.Range(1.0F, 4.0F));
     ht.Add("delay",Random.Range(0.0F, 0.5F));
     ht.Add("loopType","pingPong");
     ht.Add("easeType","easeInOutExpo");
     ht.Add("name","armWiggle");
     ht.Add("oncomplete","randomizeArm");
         iTween.RotateAdd(this.gameObject,ht);

it seems to be hitting randomizeArm before it completes the pingPong loop…