How to have players banned and not just kicked?

ik there is a banned string and all but the banned string for some reason wont ban the players its as if I don't have a string there at all there a fix to this or a line I need to add?

local speakers = {"skillfulzombie88"}
local banned = {""}

local function checkSpeakers(name)
    for _,speaker in pairs(speakers) do
        if name:lower() == speaker:lower() then return true
             end
    end
    return false
end

local function banPlayer(banner, victim)
    if victim ~= banner then
        victim:Destroy()
        banned[victim.Name] = victim.Name
    end
end

local function matchPlayer(str)
    local result = nil
    local players = game.Players:GetPlayers()
    for _, player in pairs(players) do
        if player.Name:lower():find(str) == 1 then
            --Abort if two players match the string
            if result then return end

            result = player
        end
    end
    return result
end

local function onChatted(msg, speaker)
    -- split command into the first word and the remaining words
    local cmd, args = msg:lower():match("(%w+) (.+)")

    if cmd == "ban" then
        -- words and numbers
        for word in args:gmatch("%w+") do 
            local p = matchPlayer(word)
            if p then
                banPlayer(speaker, p)
            end
        end
    end
end

local function onPlayerEntered(newPlayer)
    -- remove banned player if they try to come back in
    for _, v in pairs(banned) do
        if v:lower() == newPlayer.Name:lower() then
            newPlayer:Destroy()
        end
    end
    if checkSpeakers(newPlayer.Name) then
        newPlayer.Chatted:connect(function(msg, recipient)
            onChatted(msg, newPlayer)
        end) 
    end
end

game.Players.PlayerAdded:connect(onPlayerEntered)