I tried to make the dead body ragdoll stick with a moving road is runservice dead, help?

look i'm trying to make an obby but when player fell out of the car the dead body won't move

idk how to fix it can someone help me, thank you.

local TweenService = game:GetService("TweenService")
local part = script.Parent
local model = script.Parent.Parent
local cframelocation = script.Parent.Parent.StopLiner.Position

local Info = TweenInfo.new(
 2, -- Length
 Enum.EasingStyle.Linear, -- Easing Style
 Enum.EasingDirection.InOut, -- Easing Direction
 -1, -- Times repeated
 false, -- Reverse
 0 -- Delay
)
local Goals =
{
        CFrame = CFrame.new(cframelocation);
}
local tween = TweenService:Create(part,Info,Goals)
tween:Play()


local service = game:GetService("RunService")

local lastposition = script.Parent.Position

service.Stepped:Connect(function(_, deltatime)
    local currentposition = script.Parent.Position
    local deltaposition = currentposition - lastposition

    local velocity = deltaposition / deltatime

    script.Parent.AssemblyLinearVelocity = velocity

    lastposition = currentposition
end)

i set the script to client idk why it won't work on a dead body?

please watch the video i sent and you'll know what i mean.

https://streamable.com/exinah