on damage of player by player:

    set {pvp.%uuid of victim%} to 15

    set {pvp.%uuid of attacker%} to 15

every 1 seconds:

    loop all players:

        if {pvp.%uuid of loop-player%} is set:

            if {pvp.%uuid of loop-player%} <= 0:

                delete {pvp.%uuid of loop-player%}

                message "&6PVP가 종료되었습니다." to loop-player

            else:    

                subtract 1 from {pvp.%uuid of loop-player%}

                send action bar "&6PVP... &e[&f%{pvp.%uuid of loop-player%}%&e]" to loop-player

on command:

    wait 1 tick

    if {pvp.%uuid of player%} is set:

        message "&cPVP중입니다."

        cancel event

on quit:        

    if {pvp.%uuid of player%} is set:

        kill player

여기서 명령어 쳤을때 cancel event가 자꾸 오류가 나는데 왜그럴까요?