Problem using FMOD to play music

Hello guys. Newbie here.
I'm building a game with Essentials and i want a nice soundtrack, so midis are completely out of question (i'd consider them if i could change the soundfont). The problem is that is hard to set loop points with any other format, at least in RMXP.

Lately, i've been trying to set them using FMOD Ex and it worked perfectly, however, it's almost impossible to make any battle music to play when using the script. As soon as the battle starts, the music stops. Sometimes it doesn't even starts. And also, sometimes it plays perfectly (is that luck? lol). Map's bgms work normally.

I'm pretty sure it's something to do with either the FMOD Ex script or the battle scripts but i can't figure out what it is :X

I've attached a rar with the FModEx original script, plus another optional script (doesn't work for me anyway) and the fmodex.dll, which is needed for the code to work.

I've tried pasting them in all sorts of places on the script editor, but no success.

Any help will be greatly appreciated :D

Thanks in advance~
** and sorry if my english is bad (not my native language :P)