SpeechLib.SpVoiceClass:GetVoices does crash my Unity executable

I created a project with Unity (version 4.5.3f3). I only wrote a simple script as follow:

 using UnityEngine;
     using System.Collections;
     using SpeechLib;
  
     public class SpeechTest : MonoBehaviour
     {
         private SpVoice voice;
  
         void Start()
         {
             voice = new SpVoice();
             ISpeechObjectTokens voices = voice.GetVoices();
         }
  
         // Update is called once per frame
         void Update()
         {
             if (Input.anyKeyDown)
             {
                 voice.Speak("Hello, world!", SpeechVoiceSpeakFlags.SVSFlagsAsync);
             }
         }
     }

Here you can download the test project for Unity: https://dl.dropboxusercontent.com/u/12184013/TextToSpeech.zip

When I try to play (in Unity editor), the game runs without problems. Instead, when I build and run the game, I receive a message error:

The game crashed. The crash report folder named "2014-09-12_013622" next to game executable. It would be great if you'd send it to the developer of the game!

The zipped folder "2014-09-12_013622" is attached to this post.

When i comment this line

     ISpeechObjectTokens voices = voice.GetVoices();

the game doesn't crash after I rebuilt it.

I need to call GetVoices method, because I want to set a new voice in the "SpVoice voice" object.

Thanks in advance to everybody!