The microphone.start() function doesn't work in Android platform

The code is below, which works for Editor, but when deploy the project to android platform, it doesn't work anymore. The reason is microphone.start() function cannot start the recording correctly, so Microphone.IsRecording() always return false.

 using UnityEngine;
 using UnityEngine.UI;
 using System.Collections;
 using Help;
 
 [RequireComponent( typeof( AudioSource ) )]
 
 public class Mic : MonoBehaviour
 {
     private AudioSource audioSource = null;
     private bool toPlayOrListen = false;   // true to play, false to listen
 
     public void Start()
     {
         Button button = GetComponent<Button>();
         button.onClick.AddListener( delegate { OnClick(); } );
 
         audioSource = GetComponent<AudioSource>();
         audioSource.Stop();
     }
 
     void OnClick()
     {
         if( Microphone.IsRecording( null ) )
         {
             Microphone.End( null );
         }
         else if( audioSource.isPlaying )
         {
             audioSource.Stop();
         }
         else
         {
             if( toPlayOrListen )
             {
                 audioSource.Play();
                 toPlayOrListen = false;
             }
             else
             {
                 audioSource.clip = Microphone.Start( null, true, 10, 44100 );
                 toPlayOrListen = true;    
             }
         }
     }
 }

This happens when upgrading from unity 4.6 to unity 5.2. I cost 2 days on this and haven't found a solution. Some similar link I found is below but doesn't help. Hope can find answer by asking a question here. Thanks in advance.

http://answers.unity3d.com/questions/1083977/updated-to-unity-52-and-suddenly-my-mic-input-scri.html