Detect silence is inactive

Dear all,
I am new here and I could not find answer to my small technical problem in this forum or even in technical documentation.
I use Cubase Elements 8, instaled on Macbook Air 13 (Core i5 1,8 GHz, 8GB RAM, OSX - High Sierra), SC Steinberg UR22mkII and I am still unable to activate “Detect silence” feature for audio processing, because it is still inactive (grey) in the menu. Are there some prerequisites to take this action I don’t know?
Thank you very much for any hint or clue.

Are you highlighting the event(s) beforehand?

Regards :sunglasses:

Yes, I tried to apply this routine on an audio clip as whole, as well as on selection. The option of “detect silence” in audio processing menu is sill inactive… regards