Tile Map issue

Hi, im following a Lynda tutorial about making a tile map and im having a small issue in one of the scripts. For some reason, my script doesn't recognize a Vector2 variable called tileSize, i've watched over and over, rebuild the script as many times as i could but still got frustrated.

this is the code:

using UnityEngine; using System.Collections; using UnityEditor;

public class TilePickerWindow : EditorWindow {

 public enum Scale
 {
     x1,
     x2,
     x3,
     x4,
     x5
 }


 Scale scale;
 Vector2 currentSelection = Vector2.zero;
 public Vector2 scrollPosition = Vector2.zero;

   [MenuItem("Window/Tile Picker")]
 public static void OpenTilePickerWindow()
 {
       var window = EditorWindow.GetWindow(typeof(TilePickerWindow));
       var title = new GUIContent();
       title.text = "Tile Picker";
       window.titleContent = title;
 }

 void OnGUI()
 {
     if(Selection.activeObject == null)
         return;

     var selection = ((GameObject)Selection.activeObject).GetComponent<TileMap>();
     
     if (selection != null)
     {
         var texture2d = selection.texture2d;
         if(texture2d != null)
         {
             scale = (Scale)EditorGUILayout.EnumPopup("Zoom", scale);
             var newScale = ((int)scale) + 1;
             var newTextureSize = new Vector2(texture2d.width, texture2d.height) * newScale;
             var offset = new Vector2(10, 25);

             var viewPort = new Rect(0, 0, position.width - 5, position.height - 5);
             var contentSize = new Rect(0, 0, newTextureSize.x + offset.x, newTextureSize.y + offset.y);
             scrollPosition = GUI.BeginScrollView(viewPort, scrollPosition, contentSize);

             GUI.DrawTexture(new Rect(offset.x, offset.y, newTextureSize.x, newTextureSize.y), texture2d);

             var tile = selection.tileSize * newScale;
             var grid = new Vector2(newTextureSize.x / tile.x, newTextureSize.y / tile.y);

             var selectionPos = new Vector2(tile.x * currentSelection.x + offset.x,
                                             tile.y * currentSelection.y + offset.y);

             var boxText = new Texture2D(1, 1);
             boxText.SetPixel(0, 0, new Color(0, 0.5f, 1f, 0.4f));
             boxText.Apply();

             var style = new GUIStyle(GUI.skin.customStyles[0]);
             style.normal.background = boxText;

             GUI.Box(new Rect(selectionPos.x, selectionPos.y, tile.x, tile.y), "", style);

             var cEvent = Event.current;
             Vector2 mousePos = new Vector2(cEvent.mousePosition.x, cEvent.mousePosition.y);
             if(cEvent.type == EventType.mouseDown && cEvent.button == 0)
             {
                 currentSelection.x = Mathf.Floor((mousePos.x + scrollPosition.x / **tileSize**.x));
                 currentSelection.y = Mathf.Floor((mousePos.y + scrollPosition.y / **tileSize**.y));
                 Repaint();
             }

             GUI.EndScrollView();
         }
     }
 }

}

The issue is on Line 72 and 73 also: currentSelection.x = Mathf.Floor((mousePos.x + scrollPosition.x / tileSize.x)); currentSelection.y = Mathf.Floor((mousePos.y + scrollPosition.y / tileSize.y));

Im a noob, bear with me.

Sorry for my grammar and thank you for your attention.

ps: the Vector2 tileSize is inherited from other class called TileMap.