I use custom music in my pw
Since you can see the music in toolset, then I will assume that you have the 2da file done correctly.
Are you able to hear the music in toolset?
Eg - Choose it as the day/night music, and see if it plays?
If it doesnt play, under toolset, then it wont play under the game - they use same sort of engine.
If it doesnt play at all, then it could be a sound format issue.
BMU Files need to be mono, and less than 128k bit rate or something like that.
I cant remember for sure - the nwvault has a good app that converts the music, its not infallible, it doesnt work 100% of the time, but it is a good start.