TweenService:Create failed because Instance is null

Yeah consider asking your fellow builders first because I forgot if PrimaryPart is supposed to act as a “weld”.

Uh no apparently not. Use welds, then assign a PrimaryPart if you want.

i dont know how to make primarypart to currently existing model with no primarypart but i can confirm primarypart acts like root of the model and once root of the model changes position everything inside of that model should change the position too

  1. Insert a part, name it “PrimaryPart”

  2. Put it in the very center of the nuke

  3. Make sure all parts (except PrimaryPart) are unanchored, and have a WeldConstraint in it and its Part0 is the parent part and Part1 is PrimaryPart

  4. Anchor PrimaryPart and make PrimaryPart non collide-able and invisible

  5. Make PrimaryPart the PrimaryPart of the Model (check the Properties window)

  6. You’re done! :scream:

It says unable to cast value to object in the output even though I did all the primary stuff. Can anyone help pleaase

Wait, rename the part from “PrimaryPart” to “Center”.

After that, you can now change RNuke to the PrimaryPart.

local RNuke = workspace.Nuke.PrimaryPart

No errors in the output now, but it doesn’t do anything. It prints what I want it to print after the tween but nothing tweens

bumping cause I STILL need help. All help is appreciated thank you everyone for trying and taking time to help me

Again still need help. Is it possible to make a bunch of meshes one part?

If you group them in blender then yes, otherwise no

Can anyone group some meshes for me in blender pleaase?

You guys could of used “WorldPivot” it is a model’s cframe
Model | Documentation - Roblox Creator Hub

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RNuke is nothing, null is nothing and the reason is because of the way you find the model itself


You’re trying to index “Position” in a table (specifically a dictionary), but get children returns an array which doesn’t index values with strings, but numbers.

example of dictionary and array

dictionary = {
["Index"] = Value
array = {
[1] = Value

So you need to find a completely different way to get RNuke and make sure that it isn’t null (nil) before tweening it

Forget about the PrimaryPart. Delete the PrimaryPart, delete all WeldConstraints, and set all parts in the nuke model as anchored.

I just realized that you can set WorldPivot of the Model, credits to @Doge_boye1

Set RNuke to workspace.Nuke

local RNuke = workspace.Nuke

Now, in newPos2 change part.Position to part.CFrame, and in tween2 change Position to WorldPivot

local newPos2 = part.CFrame +,18,0)
local tween2 = TweenS:Create(RNuke, Tween, {WorldPivot = newPos2})
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Now there are no errors in the output but nothing happens

Could anyone please help? I know im dragging this on but if anyone can help I’d appreciate it I’m stuck

Yeah dude no problem.

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you need to


then it will work :joy:

grrrrrrr thats vanilla lua manual and not roblox’s luau manual