ITunes can't find Aperture Library for iPad sync

Question

I just upgraded from iPhoto '11 to Aperture 3. When trying to sync my iPad, and telling iTunes to now sync photos from Aperture, I get the following message:
"Your Aperture Library could not be found. Open the preferences window in Aperture and enable the preference to share previews with other applications."
All well and good, but when I go to the preference pane in Aperture, I do not see the referenced option. Under the "Previews" tab (Aperture > Preferences > Previews) I see the options for "Share previews with iLife and iWork" (Always/When quitting Aperture/Never)--is that the preference indication they mean? None of those options results in iTunes being able to see my Aperture library.
Oddly, Aperture can see and import photos on my iPad that are not already in my Library, but claims it cannot send photos in the other direction because the library can't be seen. Frustrating

Answer 1

This is a repost from another thread dealing with what I think is the same issue. It is what ended up working for me:
I have gone through a lot of steps and they all seem to have inched me closer to resolving this issue. My original post may have been cluttered so I'll list the steps I took here. The final step, though very time consuming seems to have corrected most of the problems, though I think I now need to get Aperture to generate new previews for all of my images at a size that the iPad likes (1920x1920).
1. Set Aperture's preference to Always share with iLife applications
2. Set Aperture's preference to generate previews at 1920x1920 or better
3. Repair Permissions via the Aperture Library First Aid function described here (http://support.apple.com/kb/HT3805). You may want to do one of the more serious Library repairs just to get things organized with the file structure system but "Repair Permissions" seems to have been all I need to do.
4. Go to the top of your image hierarchy and reprocess all of the images with the newest Aperture RAW convertor by control-clicking on Photos and selecting "Reprocess Masters"(if you shoot RAW... and you should shoot RAW). It gives you several options, I chose to preserve all of my edits which will add additional time to the process but is worth it so you don't have to re-edit everything. I selected "All Photos" and "Reprocess Existing Images"
If you have a large library (1TB or more) you are now two days or so into this process.
5. Back up your Vault to save these changes
6. Generate new previews since you changed the size in which Aperture saved the JPEGs it uses to export to Aperture. I believe this is done from the top of the image hierarchy as well by holding down the option key when you right-click on the whole library. But, I am not at this stage yet so I can't be sure about that.