My 'music cannon' switches songs in studio every 4 blasts, but not in game?

When my music cannon fires every 4 times, the music it plays is supposed to change. However, this only works in studio and not ingame for some reason. Does anybody know an explanation as to why?

while script.Parent.Parent == game.Workspace do
	math.randomseed(tick()%1*1e6)
	a = math.random(1,5)
	changesong = script.Parent.Part.SongNumber
	script.Parent.Part.Dubstep:Resume()
	script.Parent.Part.Transparency = 0.9
	script.Parent.Part.Dubstep.Volume = 0.1
	wait(0.1)
	script.Parent.Part.Transparency = 0.8
	script.Parent.Part.Dubstep.Volume = 0.2
	wait(0.1)
	script.Parent.Part.Transparency = 0.7
	script.Parent.Part.Dubstep.Volume = 0.3
	wait(0.1)
	script.Parent.Part.Transparency = 0.6
	wait(0.1)
	script.Parent.Part.Transparency = 0.5
	script.Parent.Magic.ParticleEmitter.Enabled = true
	changesong.Value = (changesong.Value + 1)
	wait(16)
	script.Parent.Part.StopFire:Play()
	script.Parent.Part.Transparency = 0.6
	script.Parent.Part.Dubstep.Volume = 0.2
	wait(0.1)
	script.Parent.Part.Transparency = 0.7
	script.Parent.Part.Dubstep.Volume = 0.1
	wait(0.1)
	script.Parent.Part.Transparency = 0.8
	script.Parent.Part.Dubstep.Volume = 0
	wait(0.1)
	script.Parent.Part.Transparency = 0.9
	wait(0.1)
	script.Parent.Part.Transparency = 1
	script.Parent.Magic.ParticleEmitter.Enabled = false
	if changesong.Value % 4 == 0 then
		print("The song number will be "..a)
		if a == 1 then
			script.Parent.Part.Dubstep.SoundId = "rbxassetid://332503821"
			script.Parent.Part.Dubstep:Stop()
			script.Parent.Part.Dubstep:Play()
		elseif a == 2 then
			script.Parent.Part.Dubstep.SoundId = "rbxassetid://244103137"
			script.Parent.Part.Dubstep:Stop()
			script.Parent.Part.Dubstep:Play()
		elseif a == 3 then
			b = math.random(1,5)
			if b == 1 or 2 or 3 then
				script.Parent.Part.Dubstep.SoundId = "rbxassetid://411440681"
				script.Parent.Part.Dubstep:Stop()
				script.Parent.Part.Dubstep:Play()
			elseif b == 4 then
				script.Parent.Part.Dubstep.SoundId = "rbxassetid://181486218"
				script.Parent.Part.Dubstep:Stop()
				script.Parent.Part.Dubstep:Play()
			elseif b == 5 then
				script.Parent.Part.Dubstep.SoundId = "rbxassetid://274682886"
				script.Parent.Part.Dubstep:Stop()
				script.Parent.Part.Dubstep:Play()
			end
		elseif a == 4 then
			script.Parent.Part.Dubstep.SoundId = "rbxassetid://252565759"
			script.Parent.Part.Dubstep:Stop()
			script.Parent.Part.Dubstep:Play()
		elseif a == 5 then
			script.Parent.Part.Dubstep.SoundId = "rbxassetid://152811077"	
			script.Parent.Part.Dubstep:Stop()
			script.Parent.Part.Dubstep:Play()	
		end
	end
	wait(2)
	script.Parent.Part.Fire:Play()
end