Why isn't my disco script not working on command?

Why isn't this working?..

local function fun() --This is the disco part
while true do
script.Parent.Color = Color3.new(math.random(), math.random(), math.random())
wait(0.5)
end

function onChatted(msg, recipient, speaker) --Function for msg

local source = string.lower(speaker.Name) 
msg = string.lower(msg)

if (msg == "disco") then    --If noob101 says disco than disco is set to true
fun = true
end

end

local source = string.lower(speaker.Name) 
msg = string.lower(msg)


if (msg == "undisco") then --If noob101 says undisco than disco is set to false
fun = false
end