iPod Shuffle Can't Sync Music

I had bought my iPod Shuffle on August last year and everything was okay until I updated my iTunes to the latest version a week ago. Previously I used windows vista but because the latest version of iTunes need at least windows 7 to be able to work, so I upgraded my vista to 7 first. But, after I've updated the windows and installed the latest iTunes, I can't sync my iPod. Whenever I press "Sync" botton on the iTunes, the windows will receive the command as if I've re-plugged the iPod into the computer. I've tried restoring my iPod to its factory setting, but nothing change. Please help me!