Square brackets are giving me a nil value?

I am trying to get my script to find a random value within another folder but on like 16 where I use square brackets, it says that I attempted to index nil ([box]) with 'Q'.

local numbersentered = {}

script.Parent.BackgroundFrame.QuestionNumber.Changed:Connect(function()

    local box = math.random(1,20)
    print(box)
    table.insert(numbersentered, box)

    for i,v in pairs(numbersentered)do
        if box == v then
            local box = math.random(1,20)
            print(box)
            table.insert(numbersentered, box)

        else
            local text = game.ServerStorage:FindFirstChild("Questions").Q[box].Value
            for  i = 1, #text do
                script.Parent.TextLabel.Text = string.sub (text, 1, i)
            end

        end
    end

end)

Any help is wonderful!