I had previously synced my entire camera roll from my iPhone to Dropbox, but recently, I went through my camera roll on my iPhone and deleted several pictures. I didn't want to go through Dropbox and do the same, so I decided to delete my entire Camera Uploads (as well as the deleted versions) and re-sync, but now, I cannot re-sync my photos again. New photos upload just fine, though. I've tried re-installing the iOS app, but no luck. What can I do?