语音识别异常“无法找到所请求的数据项，例如数据键或值

Question

我正在尝试使用c＃中的语音识别功能。我正在尝试这个代码，它的例外是

找不到请求的数据项，例如数据键或值

这是我正在使用的代码

 public partial class Form1 : Form
    {
        SpeechRecognizer rec = new SpeechRecognizer();
        public Form1()
        {
            InitializeComponent();

            rec.SpeechRecognized += rec_SpeechRecognized;


        }

        private void Form1_Load(object sender, EventArgs e)
        {
            MessageBox.Show(SpeechRecognitionEngine.InstalledRecognizers().Count.ToString()); 
            var c = new Choices();


            // Doens't work must use English words to add to Choices and

            // populate grammar.

            //

            //for (var i = 0; i <= 100; i++)

            //  c.Add(i.ToString());


            c.Add("one");

            c.Add("two");

            c.Add("three");

            c.Add("four");

            c.Add("hi");

            c.Add("hello");

            c.Add("I");

            c.Add("A");

            c.Add("B");

            c.Add("C");

            c.Add("D");

            c.Add("amer");

            // etc...


            var gb = new GrammarBuilder(c);

            var g = new Grammar(gb);

            rec.LoadGrammar(g);

            rec.Enabled = true;
        }
        void rec_SpeechRecognized(object sender, SpeechRecognizedEventArgs e)

        {

            label1.Text = e.Result.Text;

        }
    }

请告诉我为什么会出现此异常