请看下面的代码片段
using System.IO;
MemoryStream stream = new MemoryStream();
SpeechSynthesizer s = new SpeechSynthesizer();
s.setOutputToWaveStream(stream);
s.Speak("hello world");
SpeechRecognitionEngine e = new SpeechRecognitionEngine(new System.Globalization.CuntureInfo("en-US");
//Set grammar code goes here
e.SetInputToWaveStream(stream);
当它到达e.SetInputToWaveStream(stream);
时抛出错误System.FormatException: Wave file not valid
这里有什么问题?