Hi!
I´m not familiar with nuendo, but cubase - so VST system link is not the in/out you need - it´s for software chaining (or computer chaining). You need VST inputs and VST outputs to activate. Look in menu for those items and activate there the right inputs and outs (should be a stereo pair, so asio 0/1 or similar).
Other comments of nuendo users are welcome!!!
Greetings!
TravelRec.
