Unknown identifier: 'Instantiate' - weird behavior.

Hi,

I try to instantinate my game object and place it over terrain. More over I group game objets to defferents sets - for this script call special function.

Function to initializ game object:

 class gStone{
 
 var stone_01: GameObject;
 var grass_02: GameObject;
 var grass_03: GameObject;
 var grass_04: GameObject;
 var gMaterial: Material;
 var stone: GameObject;

 function getBigStone01():GameObject{

     stone = Resources.Load("Stones/bigStone01",GameObject);
     stone.transform.localScale = Vector3(4,4,4);
     return stone;
 }
 function getBigStone02():GameObject{

     stone = Resources.Load("Stones/bigStone02",GameObject);
     stone.transform.localScale = Vector3(5,5,5);
     return stone;
 }
 function getStone01(size:Vector3):GameObject{

     stone = Resources.Load("Stones/stone01",GameObject);
     stone.transform.localScale = size;
     return stone;
 }
 function getStone02(size:Vector3):GameObject{

     stone = Resources.Load("Stones/stone02",GameObject);
     stone.transform.localScale = size;
     return stone;
 }
 

}

Function to create groups:

     class gStoneGroups{
     
 var stone01:GameObject;
 var stone02:GameObject;
 var stone03:GameObject;
 var mainPos:Vector3;
 var stone:gStone;
 var botAction: botActions;
 
     var cloneStone01:GameObject;
     var cloneStone02:GameObject;
     var cloneStone03:GameObject;
     var cloneStone04:GameObject;
     var cloneStone05:GameObject;
 
 function getSimpleTerrainRotY(terrPos: Vector3){
     var terrHit: RaycastHit;
     var normal_q: Quaternion;
     terrPos.y+=20;
     
     if(Physics.Raycast (terrPos, -Vector3.up, terrHit, 10.0)){
         
         normal_q = Quaternion.FromToRotation(Vector3.up, terrHit.normal);
     }
 
     return Quaternion.Euler(270, 0, normal_q.z);
     
 }
 
 function group00(target:Vector3){
     var pos01: Vector3 = botAction.getPosAndTerrainY(Vector3(target.x+2,target.y,target.z));
     var pos02: Vector3 = botAction.getPosAndTerrainY(Vector3(target.x+6,target.y,target.z+6));
     var pos03: Vector3 = botAction.getPosAndTerrainY(Vector3(target.x+1,target.y,target.z+6));
     var pos04: Vector3 = botAction.getPosAndTerrainY(Vector3(target.x-1,target.y,target.z-6));
     
     //mainPos = target;
     cloneStone01 = Instantiate(stone.getBigStone01(), pos01, getSimpleTerrainRotY(pos01));
     cloneStone02 = Instantiate(stone.getBigStone02(), pos02, getSimpleTerrainRotY(pos02));
     cloneStone03 = Instantiate(stone.getStone01(Vector3(0.5,0.5,0.5)), pos03, getSimpleTerrainRotY(pos03));
     cloneStone04 = Instantiate(stone.getStone02(Vector3(1,1,1)), pos04, getSimpleTerrainRotY(pos04));
     
 }
 }

Function to call Group of game object:

 var stoneGroup:gStoneGroups;
 
 stoneGroup.group00(Vector3(100,100,100));

In this case I see exception:

Assets/gScripts/classes/Environment/gStoneGroups.js(37,24): BCE0005: Unknown identifier: 'Instantiate'.

Thanks