What's wrong when a virtual instrument is not responding to the keyswitch? Inserting the keyswitch in the staff doesn't work and neither does pressing the key in real time. Does it have to have a particular duration or velocity?
 
Thanks - rev

Keyswitches that I use are all short (3o ticks) and a velocity of about 100
 
I don't think either value is crucial.
 
Check that the non-responding switch is set to the correct Midi Channel

No, velocity and durstion duration are usually irrelevant. Could be just the wrong octave. That happens to me sometimes.
 
Some Kontakt instruments have visual indicators for the keyswitches, which is helpful when trying to find the right note in the PRV.
 
EDIT: "durstion", arrgh, durned smartphone keyboard...

Thanks dudes - will check.
 
rev