xfce screen lock doesn't works, I have to stop the "mate-screensaver" daemon

on my desktop I’m using XFCE, I clicked on the icon to lock the screen and it didn’nt work
googling I found

xscreensaver-settings

I launched and it says me that I have to stop the “mate-screensaver” daemon
how can I solve and have the screen locker working at start?