Странное поведение кода

using UnityEngine;
using System.Collections;
using UnityEditor;
 
public class lvlBuild : MonoBehaviour {
    public int fus;
    public int col;
    public int dv;
    private bool doing = false;
    public Camera cam;
 
    void OnMouseDown(){
        if(this.gameObject.name.Equals("Fus") && fus > 0){
            int a = Instantiate(this.gameObject).GetInstanceID();
            GameObject b = (GameObject)EditorUtility.InstanceIDToObject(a);
            b.name = "FClone";
            fus -= 1;
            doing = true;
        }
        if(this.gameObject.name.Equals("Col") && col > 0){
            Instantiate(this.gameObject);
            col -= 1;
            doing = true;
        }
        if(this.gameObject.name.Equals("Dv") && dv > 0){
            Instantiate(this.gameObject);
            dv -= 1;
            doing = true;
        }
    }
    void OnMouseDrag(){ 
        if(doing){
            this.gameObject.GetComponent<Transform>().position = new Vector3(cam.GetComponent<Camera>().ScreenToWorldPoint(Input.mousePosition).x,cam.GetComponent<Camera>().ScreenToWorldPoint(Input.mousePosition).y,cam.GetComponent<Camera>().ScreenToWorldPoint(Input.mousePosition).z + 5.0f);    
        }
    }
 
    void OnMouseUp(){ doing = false;}
}

        if(this.gameObject.name.Equals("Fus") && fus > 0){
            int a = Instantiate(this.gameObject).GetInstanceID();
            GameObject b = (GameObject)EditorUtility.InstanceIDToObject(a);
            b.name = "FClone";