Why does this chat filter not function?

There are no errors, but it just plain doesn't work.

This is the main code:

_G.Censored = {
    -- censored words
}

_G.MatchChat = function(msg)
    if type(msg) ~= "string" then msg = "" end
    for _, v in pairs(_G.Censored) do
        lower = msg:lower()
        if msg:match(" " .. v:lower() .. " ") then
            return true
        end
    end
end

There are some words in the table, but obviously they aren't appropriate.

Then I call the function MatchChat in the main chat script here:

child.Chatted:connect(function (msg)
    if not _G.MatchChat(msg) then
        -- updating chat GUI. Removed to make it easier to see the code
    end
    end) 
end)

There are absolutely no errors being returned anywhere, and it still doesn't work. I'm at my wit's end, so I came here for help.