UnityScript static variables is not a member of a script

Unity complains that : ImportWindowUI.js(21,33): BCE0019: 'modelImported' is not a member of 'UnityEditor.ModelImporter'. ImportWindowUI.js(22,26): BCE0019: 'modelImported' is not a member of 'UnityEditor.ModelImporter'. ImportWindowUI.js(22,57): BCE0019: 'modelPending' is not a member of 'UnityEditor.ModelImporter'. ImportWindowUI.js(22,87): BCE0019: 'processingModel' is not a member of 'UnityEditor.ModelImporter'. ImportWindowUI.js(25,42): BCE0019: 'modelImported' is not a member of 'UnityEditor.ModelImporter'. ImportWindowUI.js(26,58): BCE0019: 'modelImported' is not a member of 'UnityEditor.ModelImporter'. ImportWindowUI.js(27,65): BCE0019: 'ReturnProcessedModel' is not a member of 'UnityEditor.ModelImporter'.

The errors come after I put #pragma strict. But I don't think it is an issue of dynamic typing.

In addition, I also tried to declare them as public or private variables, the compiler is still throwing the same errors.

The Script I am having problems with ImportUI script:

 #pragma strict
 
 private var modelimporter : ModelImporter = (GameObject.Find("Browser").GetComponent(ModelImporter) as ModelImporter);
 
 private var menuExpanded : Boolean = false;
 private var processedModels : GameObject[];
 private var typeButton : int = 0;
 public var typeTexture : Texture[];
 
 public var skin : GUISkin;
 public var background : Texture2D;
 public var typeBackground : Texture2D;
 
 function OnEnable () {
     Debug.Log("ImportWindowUI log : Enabled");
 }
 
 function OnGUI () {
     var tempSkin : GUISkin = GUI.skin;
     GUI.skin = skin;
     Debug.Log(ModelImporter.modelImported);
     if(ModelImporter.modelImported || ModelImporter.modelPending || ModelImporter.processingModel) {
         Debug.Log("ImportWindowUI log : ModelImporter alert");
         if(GUI.Button(Rect(15, 15, 40, 40),"buildingButton")) {
             if(ModelImporter.modelImported) menuExpanded = !menuExpanded;
             if(menuExpanded && ModelImporter.modelImported) {
                 processedModels = modelimporter.ReturnProcessedModel();
             }
         }
         if(menuExpanded && processedModels.length > 0) {
             GUI.BeginGroup(Rect(15, 55, 150, processedModels.length * 50));
                 var gameobjectArray : GameObject[] = processedModels;
                 for(var i = 0; i < gameobjectArray.length; i++) {
                     if(GUI.Button(Rect(0, i*50, 150, 50), gameobjectArray[i].name)) {
                         typeButton = GUI.SelectionGrid(Rect(150, i*50, 200, 50), typeButton, typeTexture,3);
                         if(GUI.Button(Rect(350, i*50, 50, 50), "tick")) {
                             Debug.Log("ImportWindowUI log : typeButton = " + typeButton);
                         }
                     }
                 }
             GUI.EndGroup();
         } else if (processedModels.length == 0) {
             menuExpanded = false;
         }
     }
 }
 

and below is the ModelImporter Script:

 #pragma strict
 
 import System.IO;
 
 static var modelPending : Boolean = false;
 static var modelImported : Boolean = false;
 static var processingModel : Boolean = false;
 
 private var modelPaths : Array = new Array();
 private var processedModel : Array = new Array();
 private var model : GameObject;
 
 function Update () {
     if(modelPaths.length > 0 && !processingModel) {
         ImportModel(modelPaths.Shift());
     }
     if(processedModel.length > 0) {
         modelImported = true;
     } else {
         modelImported = false;
     }
     if(modelPaths.length > 0) {
         modelPending = true;
     } else {
         modelPending = false;
     }
 }
 
 private function ImportModel (path : String) {
     processingModel = true;
 
     if (Path.GetExtension(path) == ".obj") {
         // do stuff and return;
     } else if(Path.GetExtension(path) == ".dae") {
         //do stuff and return;
     } else {
         Debug.Log("ModelImporter log : Cannot process 3D model with extension = " + Path.GetExtension(path));
         // return;
     }
 }
 
 public function PostProcessModel (message : String) {
         processedModel.Push(model);    
         processingModel = false;
 }
 
 public function AddModelPaths (path : String) {
     modelPaths.Add(path);
 }
 
 public function ReturnProcessedModel () : GameObject[] {
     return (processedModel.ToBuiltin(GameObject) as GameObject[]);
 }
 

Any suggestions would be much appreciated..