When RF says there's no controller, then it doesn't see any kind of Windows game controller connected to the system.
To ensure that your USB receiver is working, first open up "joy.cpl" in Windows to see the game controller control panel applet. (Just type joy.cpl in the search box or the Start menu.)
Then, plug in your USB receiver. It should appear in that program. The Spektrum WS1000 and WS2000 would be called "Spektrum Receiver".