command /warn [ban/kick] don't work

[efred]

Hello,
in the readme.md is noted:

/warn [kick/ban] | choose what to do when the max number of warns is reached

But the command "/warn ban" or "/warn kick" don't work, to set if they should be banned or kicked, at reaching the maximum warns.
It always shows this message:

I've never seen this user before.
This command works by reply, username, user ID or text mention.
If you're using it by username and want to teach me who the user is, forward me one of their messages