google admob plugin freezes game on Quit

Hello people,
I’ve been dealing with the google admob plugin on android device. Problem is sometimes banner doesn’t show up and when that happens if i call Application.Quit(); game freezes and i have to force stop the game (phone restarts if i try to uninstall the app w/o force stoping it ). So i know theres some thing wrong with my scripting. Just can’t figure out what. Heres the last state of the code and what i tried:

public void GetBanner()
    {
        try
        {
            bannerView = new BannerView ("admob ID ",  AdSize.SmartBanner, AdPosition.Bottom);
            AdRequest getAd = new AdRequest.Builder().Build();
            bannerView.LoadAd(getAd);
        }
        catch ( Exception error )
        {
            Debug.Log( error );
        }

    }

    public void ShowBanner()
    {
        try
        {
            bannerView.Show();
        }
        catch( Exception error )
        {
            Debug.Log (error);
        }

    }
    public void DestroyBanner()
    {
        try
        {
            bannerView.Destroy();
        }
        catch( Exception error )
        {
            Debug.Log(error);
        }
    }

I call the RequestBanner() in the start function and call ShowBanner(); in the update function
and i destory the banner before quiting. i tried to put RequestBanner and ShowBanner to some of the GUI buttons i use in game ( like Play and Back ) but that way i couldnt even get it show the banner. So as far as i know theres no way to detect if banner is loaded. if theres one please tell or any other ideas, tips, i’ll much appreciate. thank you

The same problem, and I hadn’t found solution yet. Who can help me please?