Microsoft speech recognizer stops recognizing - wpf

Question

I am having trouble with the Microsoft speech recognizer. I am trying to make it constantly listen to me, and only after the word HELLO is recognized, it shows what I said. This part appears to be working, but after 15-20 seconds as the object "sre" is destroyed (as i think) the recognizer stops responding.
static void sre_SpeechRecognized(object sender, SpeechRecognizedEventArgs e)
{
List<string> words = new List<string>();
int count = e.Result.Words.Count;
for (int i = 0; i < count; i++)
{
words.Add(e.Result.Words[i].Text);
}
if (e.Result.Confidence > 0.7)
{
if (words[0].ToString() == "Hello")
{
switch (count)
{
case 2:
t.Text = words[1];
break;
case 3:
t.Text = words[1] + " " + words[2];
break;
}
}
}
}
private void InitializeSpeechGrammar()
{
t = UserMessage;
SpeechRecognitionEngine sre= new SpeechRecognitionEngine();
sre.SetInputToDefaultAudioDevice();
sre.SpeechRecognized += new EventHandler<SpeechRecognizedEventArgs>(sre_SpeechRecognized);
var grammarBuilder = new GrammarBuilder();
grammarBuilder.Append(new Choices("Hello"));
grammarBuilder.AppendWildcard();
sre.BabbleTimeout = TimeSpan.FromSeconds(3);
sre.InitialSilenceTimeout = TimeSpan.FromSeconds(3);
var CommToRecognize = new Choices();
CommToRecognize.Add(new string[] { "Red", "Green", "Blue", "Yellow", "Grey" });
grammarBuilder.Append(CommToRecognize);
Grammar g = new Grammar(grammarBuilder);
sre.LoadGrammar(g);
sre.RecognizeAsync(RecognizeMode.Multiple);
}
So, there is the RecognizeMode.Multiple mode:
sre.RecognizeAsync(RecognizeMode.Multiple);
Should I be using this mode instead? Or is there something else that I am doing wrong?