All to common this one, there are alot of devices out there that do not yet have a windows 7 driver made to support it in windows 7.
Anyway here is the link to the website and the driver downloads for your usb tv stick.
There may be one here. If not i would buy a new usb tv stick i know has windows 7 drivers for it. http://supertronindia.com/download_drivers.html