I had made a post here asking help but after some time i figure it out. I was trying to mod Dark Souls 3 with Seamless Coop but it wasn't work whatever i tried to do and then i found out you need to enable "anti-cheat support" (ptrace)
So as a suggestion i would like to include mentioning this on the FAQ. Also nitpick, the ujust script doesn't tell you to restart for to make the changes.