NGUI Volume. Slider

[easy_peasy]

Hi guys, I want to create an element with which you can control the volume of sound.
Create slider and attach code to it:

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class UIVolumeControl : MonoBehaviour {
5.        
6.         private UISlider _slider;
7.        
8.         // Use this for initialization
9.         void Start ()
10.         {
11.                 _slider = gameObject.GetComponent<UISlider>();
12.                 _slider.sliderValue =   AudioListener.volume ;
13.                 _slider.onValueChange += OnValueChange;
14.         }
15.        
16.         void OnValueChange(float val)
17.         {
18.                 AudioListener.volume = val;
19.                 print(val);
20.         }
21. }

Error occurs:
Assets/NGUI/Scripts/Interaction/UIPopupList.cs(313,43): warning CS0618: `UnityEngine.GameObject.active' is obsolete: `GameObject.active is obsolete. Use GameObject.SetActive(), GameObject.activeSelf or GameObject.activeInHierarchy.'

Many have this problem after upgrading Unity (4.3.0 use).
What's wrong? Why the error? Help! (=

[ArenMook]

You need to update your NGUI as well. Our line numbers don't match and NGUI doesn't use 'active' anywhere.