Using inverse of track to allow extraction of vocals/sounds

[MisterGump]

I have a track that I "mixed" with insertion of sounds and voices some time ago, using Audition's predecessor, Cool Edit Pro.   Since I lost the original sound/voice files, I want to extract them from the mixed track.   I have the non-mixed music track available.

A couple of tutorials mentioned you can create a multi-track session, using both tracks with the original music track "inverted", mix them and that should do the trick (ie: the inverse should cancel out the music itself).   Unfortunately, that does not work.   

How can I accomplish this with the above resources?

[SteveG_AudioMasters_]

It won't work unless the tracks are aligned to be sample accurate, and at precisely the same level. It's actually very difficult to get this to work properly in most instances.

[MisterGump]

These should be aligned as I have the original track I used to create the altered version.

Failing that, there are left and right channels -- there are several tutorials about stripping out vocals, but I want to preserve the inserted (mixed in) sounds -- they are definitely deeper and clearer in tone.  The song is rather old.   Any pointers where I can figure this out?

Thanks!