How the T.music is supposed to work?

I have an .xm music and i want to play it in the overworld...
but i don't know what to do!
because it plays the overworld music instead... I have to use no midi?
or there is something else i have to do?
then another question... what changes in the bs overworld?
EDIT: Now i tryed to use (none) as midi but now there isn't no music...
what i have to do?

^^ old post
I tryed every thing but the T.Music DOESN'T work... i need help...