An error occurred converting Final Cut XML to AAF

I have emailed you directly.
Please let us know how you get on.

This is the message I get after trying to export audio:

"Writing AAF file
Adding assets to AAF file
Adding essence for asset [Muko0360] to AAF file
Adding essence data to AAF file for portion 0 of asset [Muko0360]
Reading audio data from audio extractor : 174762 samples
Failed to read 174762 samples
Error Timed out waiting for XPC response

Suggestion: Check Console for errors.

No AAF file has been generated.
X2Pro Audio Convert 3.0.5"

It's the first time I use X2Pro (purchased it yesterday) and I even don't know where I could look for the problem!

FCPX Version: 10.2.3
OSX 10.11.3

Thanks for help!
Lisa