Why is my moving part not sticking to the character?

Code here:

local platform = p
local start = p.Position
local finish = p.End.Value
local bodyPos = p.BodyPosition

while true do
    bodyPos.position = start
    wait(5)
    bodyPos.position = finish
    wait(5)
end

It isn't sticking and I hate it what what what what ahhhhhhhhh