Either the TV stick is broken or your TV software does not like the TV stick you have.
Try downloading a copy of BlazeDTV - it is fairly cheap to buy.
I recently bought two different makes of USB Digital TV dongles - both priced the same. One had BlazeTV and the other had different TV software - not at home right now so cannot remember the name.
BlazeDTV was far superior to the other one and works with both USB TV sticks. It also lets you record the TV so you can drop it into VideoStudio / MovieFactory etc.
You can also try
Intervideo Home Theater or
InterVideo WinDVR 3
Home Theater looks and behaves rather like Windows Media Centre but I couldn't get my USB sticks to work with it, but I can't grumble as they only cost £10 each!!
I dont (think) I have WinDVR so couldn't comment on that one.