Dear everyone. There has been reported to me a few bugs in the 10.11.6 mac OS X update that hit a little bit ago. I have not yet seen bugs but then again I’m at home right now and not in lab. I suggest not to upgrade to 10.11.6 until I can figure out if/what these bugs are.
If you’ve upgraded and you have problems, delete this folder: (your-hardrive)/Library/Printers/QTR/quadtone
Then re-install quadtonerip and re-install PiezoDN. Delete your printer from system preferences and re-add it with PiezoDN.
I will know more on monday folks.