trying to mess around with the roblox lua chat and i cant even get this to work?

local util = require(script.Parent:WaitForChild("Util"))

function ProcessMessage(message, ChatWindow, ChatSettings)
    if string.sub(message, 1, 5) == "/last" then
        local currentChannel = ChatWindow:GetCurrentChannel()
        if (currentChannel) then
            currentChannel:RemoveLastMessageFromChannel()
        end
        return true
    end
    return false
end

return {
    [util.KEY_COMMAND_PROCESSOR_TYPE] = util.COMPLETED_MESSAGE_PROCESSOR,
    [util.KEY_PROCESSOR_FUNCTION] = ProcessMessage
}

this doesnet work and i pulled it right out of the freaken roblox wiki. i put this module inside messagecreatormodule like it said aswell