LA Scoring Strings 1 help

I’ve been playing with LA Scoring Strings using Kontakt 5 quite a while now and still couldn’t figure some main issue.
It says I should set a note’s velocity between 0 and 50 to get portamento sound, and above 50 to get legato sound.
Somehow, it never triggers any sound except the usual legato sound. I can’t manage to get any other sound rather than legato. The “release trigger” button is enabled. I can’t figure this out.

Any help?