An another problem - Tower Defense GUI (ver.3.)

I have a code from a tutorial on youtube (unitycookie). Somebody helped me to fix a lot of mystiping in the code but I som strange problems now that I think are related to NGUI. I am using Unity 4.0.7f pro and NGUI 2.6.4 full. Here is my code:

 #pragma strict
  
 var buildPanelOpen : boolean = false;
 var buildPanelTweener : TweenPosition;
 var buildPanelArrowTweener : TweenRotation;
  
 var placementPlanesRoot : Transform;
 var hoverMat : Material;
 private var originalMat : Material;
 private var lastHitObj : GameObject;
  
 var onColor : Color;
 var offColor : Color;
 var allStructures : GameObject[];
 var buildBtnGraphics : UISlicedSprite;
 private var structureIndex : int =0;
  
 function Start()
 {
 structureIndex = 0;
 UpdateGUI();
 }
  
 function Update ()
 {
 if(buildPanelOpen)
 {
 var ray = Camera.main.ScreenPointToRay (Input.mousePosition);
 var hit : RayCastHit;
 if(Physics.Raycast (ray, hit, 1000, placementLayerMask))
 {
 if(lastHitObj)
 {
 lastHitObj.renderer.material = originalMat;
 }
 lastHitObj = hit.collider.gameObject;
 originalMat = lastHitObj.renderer.material;
 lastHitObj.renderer.material = hoverMat;
 }
 else
 {
 if(lastHitObj)
 {
 lastHitObj.renderer.material = originalMat;
 lastHitObj = null;
 }
 }
 if(Input.GetMouseButtonDown(0)&&lastHitObj)
 {
 if(lastHitObj.tag == "PlacementPlane_Open")
 {
 var newStructure : GameObject = Instantiate(allStructures[structureIndex], lastHitObj.transform.position, Quaternion.identity);
 newStructure.transform.localEulerAngles.y = (RandomRange(0,360));
 lastHitObj.tag == "PlacementPlane_Taken";
 }
 }
 }
 }
  
 function UpdateGUI()
 {
 for(var theBtnGraphic : UISlicedSprite in buildBtnGraphics)
 {
 theBtnGraphic.color = offColor;
 }
 buildBtnGraphics[structureIndex].color == onColor;
 }
  
 function SetBuildChoice(btnObj : GameObject)
 {
 var btnName : String = btnObj.name;
 if(btnName == "Btn_Cannon")
 {
 structureIndex = 0;
 }
 else if(btnName == "Btn_Missile")
 {
 structureIndex = 1;
 }
 else if(btnName == "Btn_Mine")
 {
 structureIndex = 2;
 }
 UpdateGUI();
 }
  
 function ToggleBuildPanel()
 {
 if(buildPanelOpen)
 {
 for(var thePlane : Transform in placementPlanesRoot)
 {
 thePlane.gameObject.renderer.enabled = false;
 }
 buildPanelTweener.Play(false);
 buildPanelArrowTweener.Play(false);
 buildPanelOpen = false;
 }
 else
 {
 for(var thePlane : Transform in placementPlanesRoot)
 {
 thePlane.gameObject.renderer.enabled = true;
 }
 buildPanelTweener.Play(true);
 buildPanelArrowTweener.Play(true);
 buildPanelOpen = true;
 }
 }

And the errors that are showing:

Please help! If this problem is related to NGUI what I need to do with the code to get it working.