This is my first post. Hopefully I will have followed all the rules

I'm trying to use LayerAsAudio in version 6.0 and it always returns nil even though the IsAudioType() is returning true.
I searched the forums and found only one post with this mentioned here.
Is this expected? I'm trying to retrieve the audio file used using AudioFile() on the layer, but without a valid layer I can't do it.
Thanks,
Brett