Tycoon remove button not working ? SCRIPT BELOW

Please help me this is an very important script for me, it's just a simple thing which doesn't work. I made it work remove it and check for cash but the player doesn't have money at first time button stops working. So it's like player presses the button without having 5 cash in his value, it breaks and when he gets 5 cash the button won't ever work again, but if you have cash 5 in value and didn't press it before when u had 0 cash it will work... Why ? I made it check for money why doesn't it work ? Please guys help me i really need this and don't ignore it! thank you very much!

https://www.youtube.com/watch?v=tD9xztrc1tU ** heres a video for MORE INFO**

model = script.Parent.Parent.Parent.Door
Upgradecost = 5

local ting = 0

function onTouched(hit)
    if ting == 0 then
    ting = 1
    hit.Parent:FindFirstChild("Humanoid")

    local player = game.Players:GetPlayerFromCharacter(hit.Parent)
    if player ~= nil then
        if script.Parent.Parent.Parent.Parent.Owner.Value == player then
            if hit.Parent:FindFirstChild("Humanoid") then
                local cashmoney = game.ServerStorage.MoneyStorage:FindFirstChild(player.Name)
                    if cashmoney ~= nil then
                        if cashmoney.Value >= Upgradecost then
                        cashmoney.Value = cashmoney.Value - Upgradecost
                        model:remove()
                        script.Parent.Parent:remove()
                        ting = 0
                        end
                    end
                end
            end
        end
     end
 end

script.Parent.Touched:connect(onTouched)

Workspace.Script:2: attempt to index field 'Parent' (a nil value) <<<< bloody error ?

My guess is that i forgot to do is if the player doesn't have enough money stop the script, but how i do that ?

i've gave as much info as i can, thank you all for your time.