Speech recognition: Result.Semantic.ContainsKey is always false when reading grammar from xml file

I am studying the Microsoft.Speech library. It is similar to the System.Speech library. I am stuck with the problem and I think it might be a bug.

I tried to use e.Result.Semantic.ContainsKey("DestinationCity")

to determine if it has a key or not. When I download a grammar from GrammarBuilder, I get true

for saying "I want to fly from New York to Chicago". Then I write the grammar to an xml file and load the grammar from that file again. This time when I say “I would like to fly from New York to Chicago,” I get false

. I don't know why this is happening.

Here is my code:

class Program
{
    static void Main(string[] args)
    {
        //Create GrammarBuilder gb
        Choices cities = new Choices(new string[] { 
      "Los Angeles", "New York", "Chicago", "San Francisco", "Miami", "Dallas" });
        GrammarBuilder gb = new GrammarBuilder();
        gb.Append("I would like to fly from");
        gb.Append(new SemanticResultKey("DepartureCity", cities));
        gb.Append("to");
        gb.Append(new SemanticResultKey("DestinationCity", cities));

        //Put GrammarBuilder gb into xml file
        SrgsDocument doc = new SrgsDocument(gb);
        System.Xml.XmlWriter writer = System.Xml.XmlWriter.Create(@"C:\Visual Studio Projects\SpeechSemanticsTest\SpeechSemanticsTest\passwordGrammar.xml");
        doc.WriteSrgs(writer);
        writer.Close();

        //Create SpeechRecognitionEngine
        SpeechRecognitionEngine sre = new SpeechRecognitionEngine(new System.Globalization.CultureInfo("en-US"));
        sre.SetInputToDefaultAudioDevice();
        sre.SpeechRecognized += new EventHandler<SpeechRecognizedEventArgs>(sre_SpeechRecognized);

        //Load Grammar from xml
        sre.LoadGrammar(new Grammar(@"C:\Visual Studio Projects\SpeechSemanticsTest\SpeechSemanticsTest\passwordGrammar.xml"));

        //load Grammar from GrammarBuilder
        //sre.LoadGrammar(new Grammar(gb));

        //Start Recognizing
        sre.RecognizeAsync(RecognizeMode.Multiple);

        Console.ReadKey();          
    }

    static void sre_SpeechRecognized(object sender, SpeechRecognizedEventArgs e)
    {
        Console.WriteLine(e.Result.Text);
        Console.WriteLine(e.Result.Semantics.ContainsKey("DestinationCity"));
    }
}

      

        
        
        
      

    

The generated xml file is located here:

<?xml version="1.0" encoding="utf-8"?>
<grammar xml:lang="en-US" root="root" tag-format="properties-ms/1.0" version="1.0" xmlns="http://www.w3.org/2001/06/grammar" xmlns:sapi="http://schemas.microsoft.com/Speech/2002/06/SRGSExtensions">
<rule id="_1" scope="private">
    <one-of>
        <item>Los Angeles</item>
        <item>New York</item>
        <item>Chicago</item>
        <item>San Francisco</item>
        <item>Miami</item>
        <item>Dallas</item>
    </one-of>
</rule>
<rule id="DepartureCity" scope="private">
    <ruleref uri="#_1" />
</rule>
<rule id="DestinationCity" scope="private">
    <ruleref uri="#_1" />
</rule>
<rule id="root" scope="private">
    I would like to fly from<ruleref uri="#DepartureCity" />to<ruleref uri="#DestinationCity" />
</rule>
</grammar>

      

        
        
        
      

    

Note that there is "load grammar xml" and "load grammar from GrammarBuilder". You can do this as a comment to see the difference.