windows 7/64bit stereo mix missing [SOLVED]

Thanks. Windows 7, 64bit, on Dell Optiplex 780 //Audacity is 2.0.x series
Installation of Audacity program was accepted ok but when setting up a Record screen, the source entry blank does not display" internal stereo mix" to enable recording off current audio display of a playing movie.
The list of possible input sources only shows " microphone or" “rear/front audio input” lines in the input source blank…
I have installed the latest audio drivers for this computer already from Dell in order to serve my new audacity installation…

Try using the “WASAPI” method described here:

Thanks!! for that comprehensive tutorial. It solved my problem. I have stored it for other future problems!
It was a Windows, not an Audacity, defect.
Using the “Windows Control Panel for Sounds instructions”, I got into W7 and enabled the missing “Sterio Mix” source to be ENABLED
It records perfectly from a running video file while “speakers” audio output is going on.
Despite the 64 versus 32 Bit question, MY Audacity 2.0.x is now running well in Windows XP S3 Compatibility mode, on the ( rather awkward) Windows 7 64bit OS, by the way…