Screen no longer locked after resuming from suspend to RAM

[jis]

When I put my laptop to suspend state by closing its lid, I used to have its screen locked when I resumed. No more. I wonder why.

I am using 8.10

[jis]

For some reason, gnome-screensaver was replaced by xscreensaver. xscreensaver was installed together with lxds. I uninstalled xscreensaver and ran gnome-screensaver and now it works again.