Your alias ends with a square brace instead of a curly brace, but that would simply create an error message then continue trying to execute anything below the event.
Does it still happen if you add a 3rd channel name? Perhaps the channel requires you to already be identified to nickserv before you try to join it. Try a 3rd channel name you know doesn't exist, and use it as the 3rd one. Or try swapping the order of the 2 channels.
