I cannot get ANY of my GUIs to work in-game,they only work in solo mode on Studio?(script included)

Alright so this script makes a "Backpack" Gui that when u click it, it opens a GUI that shows your inventory. Anyone know why it ONLY works in studio solo mode, and not in-game??

. I have a Screen GUI inserted into Starter GUI, among other things, there is a frame with this local script inside it. The local script is not the only thing, But I don't feel like giving the whole thing away. This is the major script, everything else preforms simple functions.

local player = game.Players.LocalPlayer
local character = player.Character
local items = {}
local buttons = {}
game.StarterGui:SetCoreGuiEnabled(Enum.CoreGuiType.Backpack,false) 

function search(location)
    for i,v in pairs(location:GetChildren()) do 
        if v:isA("Tool") then 
            table.insert(items,v) 
        end
    end
end

function refresh()
    for i,v in pairs(buttons) do 
        v:Destroy() 
    end
    for i,v in pairs(items) do 
        local button = script.Sample:Clone() 
        button.Name = v.Name 
        button.LayoutOrder = i
        button.Parent = script.Parent.Handler 
        button.Image = v.TextureId
        table.insert(buttons,button) 
        button.MouseButton1Click:connect(function()
            if script.Parent.Handler.Selected.Value == nil or script.Parent.Handler.Selected.Value ~= v then 
                script.Parent.Frame.ItemName.Text = v.Name 
                script.Parent.Frame.ImageLabel.Image = v.TextureId
                script.Parent.Handler.Selected.Value = v
                if script.Parent.Handler.Selected.Value ~= script.Parent.Handler.Equipped.Value then 
                    script.Parent.Handler.Location.Value = v.Parent 
                    script.Parent.Frame.Equip.Text = "Equip" 
                elseif script.Parent.Handler.Selected.Value == script.Parent.Handler.Equipped.Value then 
                    script.Parent.Handler.Location.Value = v.Parent
                    script.Parent.Frame.Equip.Text = "Unequip"
                end
            end
        end)
    end
end

function backpackRefresh()
    items = {}
    search(character)
    search(player.Backpack)
    refresh()
end

backpackRefresh()

player.Backpack.ChildAdded:connect(backpackRefresh)
player.Backpack.ChildRemoved:connect(backpackRefresh)

character.ChildAdded:connect(backpackRefresh)
character.ChildRemoved:connect(backpackRefresh)