ClickDetector won't start the Tweening script

You have a few flaws in your last code posted, at least in these two lines, that I can spot:

local SlideInTween  = TweenService:Create(SlidingDoor, Tweeninfo,SlidingPanel.Cframe * CFrame.new(SlidingPanel.Size.X + 0,0, 5.3))
local SlideOutTween = TweenService:Create(SlideInTween,Tweeninfo,SlidingPanel.Cframe * CFrame.new(SlidingPanel.Size.X + 0,0,-5.3))

The flaws are in the details. And these are very specific details, that you should learn about.

Do please understand, that the TweenService:Create() method needs three arguments of the following types:

  • An instance that will be affected (usually not a Model, but a BasePart / Part)
  • A TweenInfo object
  • A “dictionary” (table) containing the property-names to affect, and what value to reach (goal).

1.
So your statement here is wrong, as the third argument is clearly not a “dictionary”, but only a CFrame:

TweenService:Create(SlidingDoor, Tweeninfo, SlidingPanel.Cframe * CFrame.new(SlidingPanel.Size.X + 0,0,5.3))

To “fix it”, you need to write the code as such (oh, I also changed the first argument):

TweenService:Create( SlidingPanel, Tweeninfo, { CFrame = SlidingPanel.Cframe * CFrame.new(SlidingPanel.Size.X + 0,0,5.3) } )

2.
Your second statement creating a tween, has even one more problem, this time with its first argument. Why do you suddenly want to tween the SlideInTween-object?

local SlideOutTween = TweenService:Create(SlideInTween, Tweeninfo, SlidingPanel.Cframe * CFrame.new(SlidingPanel.Size.X + 0,0,-5.3))

I guess it could have been a typing mistake, but the computer does not know that. So the statement should look like this:

local SlideOutTween = TweenService:Create( SlidingPanel, Tweeninfo, { CFrame = SlidingPanel.Cframe * CFrame.new(SlidingPanel.Size.X + 0,0,-5.3) } )

3.
These details were also there in colbert2677’s tutorial if you look very closely at his code samples.