itween MoveTo IndexOutOfRangeException

I'm using iTween, its amazing. Error which i'm getting is

 IndexOutOfRangeException: Array index is out of range.
 iTween.GenerateMoveToPathTargets () (at Assets/Plugins/Pixelplacement/iTween/iTween.cs:3778)

I'm calling this way

 iTween.MoveTo(gameObject, iTween.Hash("path", waypoints, "time", 4f, "easetype", iTween.EaseType.linear, "looptype", iTween.LoopType.pingPong, "onstart", "tweenStart", "onstarttarget", gameObject, "onstartparams", "", "onupdate", "tweenUpdate", "onupdatetarget", gameObject, "onupdateparams", "", "oncomplete", "tweenComplete", "oncompletetarget", gameObject, "oncompleteparams", ""));

Anything wrong in this, please guide...!!