"_G." a nil value/Attemp to index a variable starting with _G.?

I am scripting a receptionist check in and it seems to work fine in studio with a localscript, but when I test in online (or in studio testing) "_G." becomes nil or I get an error "attempt to index a nil value," a variable which has _G. in front of it.

script:

script.Parent.Parent.Submit.MouseButton1Click:connect(function()

for i,v in pairs(game.Players:GetChildren()) do
    print("Finding User")
    if v.Name == script.Parent.Parent.UsernameInput.Text then
        print("Found User "..v.Name)
        local CurrentUserServing = v.Name
        _G.CurrentUser = v
    end
end

print("Next Step")

------------ FOR CHECK IN 
if script.Parent.Parent.TableType.Text == "Normal" then
    print("Table Type Collected")
    if script.Parent.Parent.SeatNumber.Text == "Two" then
    print("Table Info Established")

    local Card = Instance.new("Tool")
    Card.Name = script.Parent.Parent.NumberOfTable.Text.." [] 2 Seater"
    Card.RequiresHandle = false
    Card.Parent = _G.CurrentUser.Backpack

    for i,v in pairs(game.Workspace.ReceptionBoard2.MainBoard.SurfaceGui.BackgroundFrame:GetChildren())do
        if script.Parent.Parent.SeatNumber.Text == v.Name then
            v.Occupation.Value = true
            v.Occupation.Value = false

            local NameToHold = Instance.new("StringValue")
            NameToHold.Name = "UsernameOwner"
    NameToHold.Value = _G.CurrentUser.Name
    NameToHold.Parent = v   
        end
    end
    end
    end

end)

Thanks!