I have been using Cubase for years, so I’m very familiar with how to export audio, but after upgrading to LE9, my mixdowns are silent. I tried mixing down to wav (nothing is muted, beginning/ending are set, etc) but the wav file, while displaying the right length, is completely silent.
Except for LE9 you have not given any info about your software, hardware, computer setup, or track routing. Without any of that we would just be guessing. So try to provide that information and some screenshots to help us understand your predicament.