What is the problem with this Tween, CFrames and Welding combo?

Hello guys! So I welded 3 part into one (as a test), and wanted to see how will it move with CFrames. I have Part1, Part2, Part3. Im using Tweening. I dont understand, what is the problem. In Part2 and Part3 are 1-1 WeldConstraint, it is welded how it should be. The position is good too, so i dont know... Part2 and Part3 are welded to Part1, if I try this with Vector3, the Part1 moves good, but as I know, you need to use CFrame to move welded objects, and if I set to CFrame and press the button nothing at all happens. This is the code:

local TweenService = game:GetService("TweenService")

local Position = {}
Position.CFrame = CFrame.new(44.3, 0.5, 80.9)

local Part = script.Parent

script.Parent.ClickDetector.MouseClick:Connect(function()
    local LinearOut = TweenInfo.new(2, Enum.EasingStyle.Linear, Enum.EasingDirection.Out, 0, false, 0)

    local Tweening = TweenService:Create(Part, LinearOut, Position)
    Tweening:Play()
end)

Anyone know what is the problem? And one thing I didn't said, the 3 parts are in a group, and yes, the primarypart is Part1