Client Borders

[hh07]

I tried to use client borders with skellet but its not working I used the example Skript from skellet but its not working either

command /setlocation:
    permission: permission.text
    trigger:
        set {UHC.Center} to player's location
    
command /b:
    trigger:
        set client border warning distance of player to 100
        set client border center location of player to player's location
        broadcast "&6%client border center location of player%"
        broadcast "%client border size of player%"
        loop 20 times:
            set client border size of player to loop-number
            broadcast "%client border size of player%"
            wait a second
        reset client border warning distance of player

that's the example Skript from skellet but I get error messages like "Cant understand condition: set client warning distance" or "Cant understand this expression: broadcast "%client border size player%"