Problem with stereo mix on Windows 7

Hello
I have a problem in Windows 7
I would like to get stereo mix on, I’ve followed a lot of steps that was recommended in some of sites and some of the videos in YouTube, but unfortunately no result …
I would like simply to get the property stereo mix on in the Audio section …
Had previously pressed in place and tree choice shows , but does not show anything about stereo mix
I linked 2 images, the 1st one shows what I have and the 2nd what I should have
any suggestions please
image N° 1
image N°2

