I have been trying to get this to work myself too for a few days now, and followed the instructions on Apples tech support site, and all over the internet. I've come to the conclusion that it must be an issue either on my Windows machine or with my router. I've yet to pin point it though.
For now I've ended up buying a 32gb USB thumb drive and just transfer files back and forth. Its slower, but less of a headache and i've been meaning to get a large thumb drive for sometime now.