Unable to find or record using Stereo Mix

[vijay1700]

I have Win7, 2.1 Speakers, 1 Stereo Headphone with Mic. Everything is working fine. I have connected my speaker jack and the headphone jack to system via a splitter and the Microphone jack of my headphone to the next female connector (Pink) of the system, but when I tried to record a karaoke video song (with no vocals) with my voice through my headphone Mic (which I have many a times while using XP SP3), it is not able to record the playback/background music and is recoding just my voice...how to solve this, and also, I am unable to find or record Stereo Mix in Recording Devices even after clicking Show Disabled Devices and I have no problem with audio driver, as it is up to date...can anyone help?

[steve]

How are you playing the karaoke video song?
Which version of Windows are you using?
Which version of Audacity are you using (look in Audacity "Help menu > About Audacity")
What sort of microphone are you using and how is it connected to your computer?