DirectSound (C++) playing only some Midis

Just a quick message -
I am writing a simple Game using OpenGL for graphics, and DirectX for sound and input. I've written a basic DirectSound engine that uses a single IDirectMusicPerformance8*, IDirectMusicLoader8* and IDirectMusicSegment8*
However, it seems to only be able to play some midi files and not others. To make matters worse, when i tried to add a track to the file it would play, this track could not be heard.
Are there special rules regarding files/channels used which allow a midi to be played in DirectX??
thanks \