Just a guess, but you may have to downsample that extra audio to 16-bit 48K sample rate-- which I assume is the full spec for your camera's audio.
You can do this by selecting the 24-bit audio files inside FCP and collect them in a Batch Export window. Change the audio settings to 16-bit 48K (or whatever the sample rate of your camera audio) and Export. Then reimport the downsamples and try a merge with those.
While FCP has an "open timeline" it's always nice to get all the materials into it in one "language."
- Loren
Today's FCP keytip:
Invoke your Opacity/Audio Levels Adjust dialog with
Command-Option-L !
Your Final Cut Studio KeyGuide? Power Pack.
Now available at KeyGuide Central.
www.neotrondesign.com