hey eja,
The short answer to your question is, 'no.' The Sound and Vibration Toolkit is not the culprit in this situation. Check in your application builder to ensure that 'Run When Opened' has a checked Value Option. By default it will probably be set to, 'Use VI Setting,' which may not run the dll when called from a C# application. You'll need to deselect this checkbox before setting the value to true.
Let me know how this works out. Hope this solves your problem!
Have a great day,
Elijah Kerry
NI Director, Software Community