When I mixed down the song normally (without freezing that track), for some reason the envelopes I had added didn't make the sound of it change as it played back.
It plays back inside Sonar 7 ok before it is mixed down though.
Then I tried to freeze the track, and then mix the song down, still didn't work.
Eventully, I tried out using "Bounce to Track" in Sonar, it bounced the Sylenth1 audio to another track,then mixed down my song, and then it worked. What a pain, I spent a couple hours trying to figure it out.
