When you say the green light is working are you referring to the ones on the plugin or rack slot on the right side? If they are flashing on the plugin slot then open a MIDI monitor on the plugin MIDI input and see if MIDI note messages are reaching the plugin.
It could explain but not sure. It is saying that on a scan by Cantabile for files it requires that there is no permission to access the folder where some of the VST instrument data is stored. We need to know what plugins you running and if you are using racks to be more able to help out.
It look like only a few of my vst don’t work this way, but it’s the main that I’m using …
Kontakt
omnisphere/keyscape/trilian
VB3-II
I tried them in a rack or without, tried them on a new song but still it only work with the on screen keyboard and not my midi keyboard. and this issue is only with cantabile
I tried to reinstall Kontakt but it’s still the same
Other vst seems to work just fine with my midi keyboard
have you checked inside the rack, if the MIDI messages propagates correctly up to the plugin input? Make sure also that the plugin is in OMNI mode and, if this is not the case, that the incoming MIDI messages are on the same MIDI channel that the plugin is supposed to respond to (use the MIDI monitor for the check).
Is the MIDI channel used by your Keylab mkII the same used by the onscreen keyboard?
I agree with Gabriel, from your picture it appears that the breakdown in the audio chain is inside the rack named “piano”. Open the rack and check further or post us a pic of it.