The error message you are getting indicates that there is no language pack installed on your Windows Operating System that can support speech recognition.
In windows 7 the following languages are supported "English, French, Spanish, German, Chinese, Japanese"
I am not familiar with Windows Home Server, but if you have the German Language Pack installed I would expect it to work. Are you able to run windows built-in speech recognition? Usually if you can run that, you won't have problems with VoxCommando.