How to make a chat group wall?

I have been trying to figure out how to make a wall that when you chat wallon it turns the wall can collide to true and transparency to 0 I got some of it figured out but I want it to work in a certain group at a certain rank. Heres the code I got so far.

local wall = game.Workspace:WaitForChild "Wall"

local players = game:GetService "Players"

function chatted(msg)
    if string.lower(msg) == "wallon" then
        wall.Transparency = 0
		wall.CanCollide = true
    elseif string.lower(msg) == "walloff" then
        wall.Transparency = 1
		wall.CanCollide = false
    end
end

game.Players.PlayerAdded:connect(function(player)
    player.Chatted:connect(chatted)
end)