No background music during gameplay

[BboyRHan]

I couldn't solve the problem of DTXmaniaV3 not being able to play AVI, so I tried to play it with DTXmaniaNX, but I had the same problem as the earliest V3 version of the game not being able to play the background music (the music problem of the V3 was solved after installing the codec).
My situation is that the original V3 version can't play AVI but can play background music normally, while DTXmaniaNX can't play background music but can play AVI normally.
Is there any way I can get DTXmaniaNX to play background music during gameplay, and do I still need to install any audio codec?