iTunes doesn't detect iPad 2 and iPhone 4

After I updated my iOS devices (iPad 2 and iPhone 4) to iOS 6, is difficult that iTunes detects them through Wi-Fi.

I have to restart iTunes or my iOS devices so iTunes can detect them.

I updated to iOS 6, I didn't do a clean install. My MacBook Pro is fully updated (10.8.2 and latest iTunes 10.7).

Does anyone else has the same problem?

Thank you in advance.