Why does the CFrame stop working after a while?

If I CFrame a part to my character then it works for a short period of time and then it just falls onto the floor...

Why is that????

local LocalPlayer = game:GetService("Players").LocalPlayer
local Character = LocalPlayer.Character or LocalPlayer.CharacterAdded:wait()

game:GetService('RunService').RenderStepped:Connect(function()
	
script.Parent.CFrame = CFrame.new(Character.Torso.Position)
                       

end)