You've probably configured the recording input settings in a wrong way. For most of the new sound cards, a new component needs to be enabled in the Recording tab. That component is called Stereo Mix. Right click the sound icon on the system tray, then go to Recording. Right click inside the components area and select Show Disabled Devices. The Stereo Mix should appear. If it doesn't then it means you will need a new driver for your sound card.
It should look like this:
Once it's enabled, start Amolto Call Recorder and select Stereo Mix as input tool.