UI custom music won't work

So I wanted to change my FSX UI music for the startup to something custom, not just the FSX001 and all those. So I imported a .wav file into the C:\Program Files\Microsoft Games\Microsoft Flight Simulator X\Sound\UIMusic folder, closed the folder, then opened FSX. After selecting the new music file in sound settings, it just went silent. All other default music files are working fine, but the custom one wont play while in FSX. I already checked to make sure that the file itself would play, and it worked fine in my computer's music player. But it wont work in FSX. Help anyone? I am running Microsoft Windows XP, Media Center Edition, Version 2002, Service Pack 3. My .cfg file has only been changed to remove the brakes info that pops up in the corner during flight, so the .cfg file is basically untouched. I dont know if this is useful, but my computer info is as follows: eMachines T6524, AMD Athlon 64 Processor 3400+, 2.19 GHz. 1.37 GB RAM. Thanks!