iTween and texture problem

I have scale GUI plane to make effect but it happen that the texture become black when scaled.

 public GameObject icebar;
 Hashtable ht = new Hashtable();    
 
 void Start () 
     {
         
         iTween.Init(iceHead);
         iceHead.renderer.enabled = true;
         appear();
     }
 
 
     private void appear()
     {    
         ht.Add("time",0.2);    
         ht.Add("scale",new Vector3(3,3,0));
             ht.Add("onComplete","appear");
         ht.Add("onCompleteTarget",icebar);
         ht.Add("easetype","easeOutCubic");    
         iTween.ScaleFrom(iceHead,ht);    
         ht.Clear();    
     }

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as you can see in the picture this after using iTween.ScaleFrom(iceHead,ht); the texture become black, i don't know why. the ice bar sometimes get black too.