How do I make music play during a cutscene, then make a different one play after it?

So I was making an RPG with a cutscene, and I can't get different music to play during or after a cutscene. The only cutscene I have is the one when you join, so needing to make it play more than once is out of the question. Here is my code:

cutscene = script.Parent.Parent.PlayerGUI.Cutscene
mainMusic = script.Parent.Parent.PlayerGUI.MainMusic
if cutscene.isPlaying then
	wait(1)
	print "Playing"
else
	mainMusic.Playing = true
end

--LocalScript is in StarterPack --Music are in StarterGUI, which is linked to PlayerGUI

So basically, it won't print "Playing", and it won't play mainMusic either.

Cutscene music isn't looped. mainMusic is, Please help!!!

Can you give me the code, and explain it so i can use it quick, but can do again later?