VS 2017 выдает ошибку на функцию e.Result.Confidence > 0.82

namespace WindowsFormsApp26
{
   public partial class Form1 : Form
   {
    public Form1()`        {
        InitializeComponent();
    }
    static void sre_SpeechRecognized(object sender, SpeechDetectedEventArgs e)
    {
        if (e.Result.Confidence > 0.82) l.Text = e.Result.Text; 
    }
    private void Form1_Shown(object sender, EventArgs e)
    {
        System.Globalization.CultureInfo ci = new System.Globalization.CultureInfo("ru-ru");
        SpeechRecognitionEngine sre = new SpeechRecognitionEngine(ci);
        sre.SetInputToDefaultAudioDevice();
        sre.SpeechRecognized += new EventHandler<SpeechRecognizedEventArgs>(sre.SpeechRecognized);
        Choices colors = new Choices();
        colors.Add(new string[] {"Один","Два","Три","Четыре","Пять","Шесть"});

        GrammarBuilder gb = new GrammarBuilder();
        // gb.Culture = ci;
        gb.Append(colors);
        Grammar g = new Grammar(gb);
        sre.LoadGrammar(g);
    }
  }
}