Microsoft.Speech SpeechRecognitionEngine.setInputToDefaultAudioDevice() method throwing System.InvalidOperationException

[Code Apperentice]

This isn't really C++, it's C#, but help is appreciated!

I'm using Microsoft.Speech (NOT System.Speech!) and I'm trying to set the input of the audio stream to my microphone, which is the default audio device, but it is throwing the exception:

System.InvalidOperationException' occurred in Microsoft.Speech.dll but was not handled in user code`

Additional information: Cannot find the requested data item, such as a data key or value. 

This was just a test, ideally I want to set the audio stream to my speakers, but if I can get this to work I can just use a virtual audio device software to plug into the mic stream. If anyone can also set the audio stream to the speakers directly, that would be perfect.

Your help is appreciated!