Midi regions

when, as stipulated in the manual, after having selected the elements which must become a midi region, I press ) which is supposed to open a popover in which I must enter the notes which will be
concerned. In fact, when I press ) no popover appears, and the notes are flat.
I upgraded to Dorico 5 for this feature and it doesn’t work, or things are poorly explained.
How to solve this problem ?

Are you in Write mode, and what keyboard language are you working with? The manual specifies Shift-0, which on an English keyboard is the ) character, but I wonder if you might be working with a different keyboard language that needs a different shortcut.

Either way, in Preferences > Key Commands you should be able to set your own command (it’s Note Input > Create MIDI Trigger Region).