Hello cuartetto,
Is it the full retail version of PowerDirector/Director Suite you're using? I ask because the trial version does not install WaveEditor, which would explain why it's greyed out.
In PowerDirector, you can only export a single clip to AudioDirector at a time.
One way around this, to achieve your purpose, would be to produce your PD project to an audio only format (WAV, WMA etc) and import that file into AudioDirector for editing.
PIX
PIX YouTube channel