Why dose KeyDown on / not work?

local Player = game.Players.LocalPlayer
local Mouse = Player:GetMouse()

Mouse.KeyDown:connect(function (key)
    if string.byte(key) == 47 then 
        print("Chat Opened")
        script.Parent.TextBox:CaptureFocus()
        end
end)


script.Parent.TextBox.FocusLost:connect(function()
    if string.sub(script.Parent.TextBox.Text, 1,1) == "/" then
        print(Player.Name .. " Ran a command")
          workspace.ChatX.AdminByLua.Commands:FireServer(Message, Player)
    else
        x = script.Parent.TextBox.Text
        y = Player.Character.Name
  workspace.ChatX.Chat:FireServer(x,y)
print(x,y)
    end
end)

When i press / in studio test its works but when im online it dosnet work