Hi,
I am also having the same troubles, I can’t get any other demo apart from Demo 1 to work, the one that plays all the files. I am trying to find out what libraries actually work for playing and individual file. Seems like many people are having trouble it geeting these shields to work following the wiki instructions. Just to make it more confusing there is this wiki site too?
http://www.seeedstudio.com/wiki/Music_Shield_V2.0 It is rather confusing all this and I don’t normally have any troubles in getting products from SeeedStudio working.