AmbientMusic.2da - you must have each track on a new row, with a new unique number.
I just shove mine in the override directory, but hak or override directory will do the same job.
EDIT: Ah well, and I've named my file mus_bat_hdt04 (no more than seven characters in the actual name).
The file name of the music file, needs to be less than 15 characters (including the extension - I think).
mus_bat_hdt04 = 13 + .bmu = 17
Variable Bit Rate- I somtimes get the same warning - it doesnt always cause problems, but I usually try to force the bitrate when I save or export the audio to 128 kbs.
These are the 3 reasons I have experienced that caused music not to play.
Anyone know how to get music to appear in the battle music section/dropdown?
Thats the one dropdown I cant get it to appear in.