Spectate Gui Only Works in studio? Any help?

Works in studio great :D, However not in actual gameplay.

Here is the script:

cam = game.Workspace.CurrentCamera

local bar = script.Parent.Bar
local title = bar.Title
local prev = bar.Previous
local nex = bar.Next
local button = script.Parent.Button

function get()
    for _,v in pairs(game.Players:GetPlayers())do
        if v.Name == title.Text then
            return(_)
        end
    end
end


local debounce = false
button.MouseButton1Click:connect(function()
    if debounce == false then debounce = true
        bar:TweenPosition(UDim2.new(.1,0,0.77,0),"In","Linear",1,true)
        pcall(function()
                title.Text = game.Players:GetPlayerFromCharacter(cam.CameraSubject.Parent).Name
        end)
    elseif debounce == true then debounce = false
        pcall(function() cam.CameraSubject = game.Players.LocalPlayer.Character.Humanoid end)
            bar:TweenPosition(UDim2.new(-.3,0,0.77,0),"In","Linear",1,true)
        end
end)

prev.MouseButton1Click:connect(function()
    wait(.1)
    local players = game.Players:GetPlayers()
    local num = get()
    if not pcall(function() 
        cam.CameraSubject = players[num-1].Character.Humanoid
        end) then
        cam.CameraSubject = players[#players].Character.Humanoid
    end
pcall(function()
                title.Text = game.Players:GetPlayerFromCharacter(cam.CameraSubject.Parent).Name
        end)
end)

nex.MouseButton1Click:connect(function()
    wait(.1)
    local players = game.Players:GetPlayers()
    local num = get()
    if not pcall(function() 
        cam.CameraSubject = players[num+1].Character.Humanoid
        end) then
        cam.CameraSubject = players[1].Character.Humanoid
    end
pcall(function()
                title.Text = game.Players:GetPlayerFromCharacter(cam.CameraSubject.Parent).Name
        end)
end)