Music Manager won't change music?

The music won't change when the variable updates, can you help me?

loop = true
local Sound = script.Sound
id = 0
playingid = 0
wait(1)
local stage = script.parent.parent.CheckPointNumber.Value
while loop == true do
    if stage > 0 and stage < 2 then --Song1 
    id = script.Song1.Value
end
    if stage > 1 and stage < 3 then --Song2
    id = script.Song2.Value
end
    if stage > 2 and stage < 4 then --Song3
    id = script.Song3.Value
end
    if stage > 3 and stage < 5 then --Song4
    id = script.Song4.Value
end
    if stage > 4 and stage < 6 then --Song5
    id = script.Song5.Value
    end
    --Play--
    if id ~= playingid then
    Sound:Stop()
    Sound.SoundId = "http://www.roblox.com/asset/?id="..id
    Sound:Play()
    playingid = id
    end
    wait(1)
end