One thing to check before you start is that the crosspoints matrix of your audio cue is routing the channels of your file to all the outputs that you will eventually want to hear them on.
For example, a single-channel (mono) audio file will, by default, only be routed to the first output of the cue, so only that output could ever get any audio signal to it (unless a fade cue is used to change the routing).
Thus, one way you could use fade cues to redirect audio is by fading up and down the actual crosspoints to reroute the signal from the one channel to the various outputs.
Does that help?
-C