On some newer computers the FCD may be recognised as an audio device but not as a HID so that frequency control does not work.

First:-

Check that the FCD appears as an audio device in "Device Manager".

It should also appear as a HID but that is not so easy to confirm, use FCHid See below.

Then check for a USB problem.

Howard, the FCD designer, says here:-  http://www.funcubedongle.com/?page_id=1225 part way down.

"We believe that it’s to do with USB 2.0 hubs that use a single transaction translator rather multiple transaction translators for multiple USB 1.1 devices like the FCD & FCD+. There’s a treatise on this here:http://www.tomshardware.com/reviews/usb-technology,677-3.html

So there are many ways to resolve this if the assumption above is true. For example you can try moving the FCD+ onto a different hub, or other USB 1.1 devices on that hub to a different hub. You could also use an additional USB 2.0 hub (or an active USB 2.0 Extender which is really just a one port USB 2.0 hub) that daisy chains off the existing FCD+ port and plug the FCD+ into the new hub."

Note:- "Moving onto a different hub" is referring to the computer's internal USB hubs as well as any external hubs. Moving USB devices to different sockets may provide a solution.

:- The FCD is a USB1 device. New systems, particularly those with USB3 do not support USB1 properly.

It has been noted that a USB mouse receiver has stopped the FCD working. Remove all other devices and try.

Maybe a few extra suggestions and notes here.  Look here for some work-rounds. And some other problems noted.

The FCD being seen by Windows but not working:- First make sure the FCD is selected as a Recording Device in Windows.
If there is an audio level slider about 10-20% may be about correct but may need resetting once you become familiar using it.

FCHid

This page shows the FCHid2.002 control/test program. NOTE DO NOT TRY TO UPDATE THE FIRMWARE.

Programs requiring a DLL

If these tests are passed and the FCD is not controlled by a SDR program like HDSDR that needs a DLL:- Check you have the correct DLL and that this is installed correctly. Ensure that it is unzipped and put into the correct folder. Windows and some anti-virus programs may block this downloaded file. Right click, "Unblock". Check your anti-virus settings.