Why is this part not moving when using a BodyPosition?

Im trying to make a part move between one part and another part but when I test it the part stays it one place and im using a BodyPosition and the part is not anchored.

Here is the script I used

local BodyPosition = script.Parent.BodyPosition
local Start = script.Parent.Parent.Start
local Finish = script.Parent.Parent.Finish

while true do
    BodyPosition.Position = Start.Position
    wait(1)
    BodyPosition.Position = Finish.Position
    wait(1)
end