can recognition free dictation?

Question

i use System.Seppch.Recognition

this is my code for free code

Grammar dictationGrammar = new DictationGrammar();
recognizer.LoadGrammar(dictationGrammar);
recognizer.SetInputToDefaultAudioDevice();

but.. this out wrong data

is it I am Korean andEnglishnot good?

To use recognition free speech, how it is done?