tweenservice:create failed because instance is null what is wrong?

I just started learning code and I wanted to make a tween. But I get a error it says tweenservice:create failed because instance is null how do I solve this?

local tweenService = game:GetService('TweenService')
local part = script.Parent

local tweeningInformation = TweenInfo.new(
	5,
	Enum.EasingStyle.Bounce, --easing style of tween
	Enum.EasingDirection.Out, --direction of the tween
	10,
	true,
	2
)


local partProperties = {
	Size = Vector3.new(20,20,20);
	Color = Color3.new(255, 0, 0);
	Transparency = 0.5	
}

local Tween = tweenService:Create(Doort,tweeningInformation,partProperties)

Tween:Play()

At this line

local Tween = tweenService:Create(Doort,tweeningInformation,partProperties)

you never called the object "Doort"

You can change line 2 from

local part = script.Parent

to

local Doort= script.Parent

or you can change

Line 20 from

local Tween = tweenService:Create(Doort,tweeningInformation,partProperties)

to

local Tween = tweenService:Create(part,tweeningInformation,partProperties)