The different speech engines work differently.
If you want to run VC using a different engine from the one in which you originally built your commands:
purge your cache and rebuild your grammars.
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This has nothing to do with program "bugs". This has to do with compiling your grammars properly to work with the language engine you are trying to use.
Note also: If you want to use
VoxCommandoSP.exe (the new, Windows Speech Platform 11), you will need to download the appropriate language pack(s) from the Microsoft site, and not just the runtime engine. This is true even if you're planning to use English only.
As per the video tutorial and the wiki documentation, when you run VC2 SP version for the first time and select your language engine in Options, do not select the "lightweight" speech recognizer that Microsoft automatically installs with the runtime engine. You need to choose a proper, full speech recognition engine.
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Old news to some of you, but hopefully repeating the message will save us all some time and headaches.