[Solved] Chartboost ad is not working when reloading scene

Hi. I am trying to integrate Chartboost Ad into my game.

I have added interstitial Ad & rewarded video code. Both Ad work fine when i first start up the game. However, both Ad do not work after i called Restart ().

I am using Unity version 5.1.1 and the newest Chartboost SDK version 5.5.3

My workflow:

Interstitial Ad is shown when player lose the game. Lose () is called in this situation. Rewarded video is shown when player press EarnCoin button. EarnCoins() is called when the button is pressed. Restart() is called when restart button is pressed.

My code:

 private int frameCount = 0;
 void Start () {
                Chartboost.cacheInterstitial(CBLocation.Default);
                Chartboost.cacheRewardedVideo(CBLocation.Default) ;
                Chartboost.setAutoCacheAds(true);
 }
 
 void Lose () {
                  if (Chartboost.hasInterstitial(CBLocation.Default)) {
                Chartboost.showInterstitial (CBLocation.Default);
                  }
 }
 
 void EarnCoins () {
 
         if (Chartboost.hasRewardedVideo (CBLocation.Default)) {
             Chartboost.showRewardedVideo (CBLocation.Default);
                  }
 }      
     
 void Restart () {
         Application.LoadLevel (Application.loadedLevel);
 }

 void Update () {
            frameCount++;
 
            if( frameCount > 30 && Chartboost.hasInterstitial(CBLocation.Default) == false){
             Chartboost.cacheInterstitial(CBLocation.Default);        
             frameCount = 0;
         }
 
             if( frameCount > 30 && Chartboost.hasRewardedVideo(CBLocation.Default) == false){        
             Chartboost.cacheRewardedVideo(CBLocation.Default);    
             frameCount = 0;
         }

I have used ChartboostExampleScript to check. Everytime i play the game as the 1st time, both Ad can cache automatically. However, after i pressed restart button, both Ad can't cache automatically. Chartboost.hasInterstitial and Chartboost.hasRewardedVideo keep showing "false" in the log.

Do you guys have any ideas? Any suggestion would be appreciated :]