I have successfully used the Audio Parameter many times, but for some reason it is not working now. I set up everything as normal, attach the behavior to an object and add an audio track to it. For some reason when I play the track or use the play button in the behavior window, the output meter shows no output. It does not move, and the parameter seems to have no effect on the object at all. I've tried restarting motion and doing different project setups and different audio tracks and it's always the same. I'm wondering if anyone might have some insight.
If you haven't already, check to make sure the Apply To section is not still set to "None." I believe it's the bottom selection in the inspector under behavior.
One note to everyone using the Audio Parameter, the parameter does run into issues when you try and apply the parameter to multiple objects (it can depend on your system, but 10 seems to be about the workable limit with the same audio track). Too many objects, and it appears Motion is over processing the behavior. It acts as if each instance of the parameter has to reinterpret the audio independently throughout the animation (regardless of the parameter length) draining a lot of resources, even with the same audio clip. You can see the problems if you look at the key frames as all the curves will change to already locked objects when you apply the behavior to an additional object. It's frustrating.