This has been posted before but because of the numerous reports of syncing wireless to windows itunes I mention it again
First when booting windows make sure itunes in not set to start automatically.
The windows file "Apple mobile devices" will load at boot.
After windows is fully booted start iTunes.
Having iTunes start automatically is the cause of wireless sync failure. This is because having iTunes start before the Apple mobile devices file loads in windows prevents iTunes from finding your iPad.
One other area to check is that see that the ports 3689 and 5353 are open in any firewall you use including the
wireless router you are using.
I do not make any claim for this solution but only a reminder of the cure.
The original cure for this problem was poster by user "Davemoore" last December