Not syncing automatically in iTunes

Hi!

I have a windows 7 pc and itunes is uptodate but it's not syncing my iphone 5s automatically. The option "open itunes when this iphone is connected" is ticked and "Prevent iPods, iPhones and iPads from syncing automatically" is not ticked.

When I connect my iphone, itunes is opening by itself but not syncing automatically.

I have uninstalled and reinstalled itunes but the issue persists. I have created a new admin user account in my pc and same issue is happening.

I have uninstalled the AVG anti virus software but same issue.

I can sync and backup my iphone manually but not automatic. Same behavior with my iphone 4s.

I hope someone can help me. Thanks!