I think I found the problem.
The situation is as follows:
iPod photo cache
On the system exist two different users which want to synch the folders A, B and C with different devices iPad and iPad mini under their accounts. But the fist device created the folder iPod photo cache into "pictures"and this could be the reason hwy the second evice cannot synch the same photos.
May you follow my idea and do you have an answer how can I solve the problem?
i see what you are saying but i have an iPhone and iPad and they both sync pictures fine.
Just wondering if it is worthwhile deleting the iPod Photo Cache. This will not affect your existing photos but will force iTunes to rebuild this cache when it exports.
Details on how to find it here