The engine will not see music files

[temnix]

I made some custom music, made the playlist, copied, installed, everything quite like for another track, before. It's music for an area. But this time the engine refuses to see the files in the playlist. The playlist itself is loaded, assigned to the area, but the files on it are "Not found." They are there, in the Music folders of Near Infinity, which can play them, but View/Edit inside the areas fails. Trying to get to the root of the problem, I simplified the playlist, made it include just one tune, and that tune's file I also replaced with one of the game's defaults, in case this was the fault of the audio, after all. And still nothing. Right now the playlist simply reads:

LT1_#
1
1

And the file in the corresponding directory is called LT1_#1.acm. I had the notion that my suffix, _#, has the misfortune of being rejected by the music function, but I've had another track installed and playing successfully with the UN_# header and prefix. So I can't understand what the hell the engine wants here. Has this happened to someone else?