HP Computer and Line Inputs

[Elspode]

I'm totally baffled on this one. My HP desktop, the one I got a year and half ago, has front R/L Audio inputs. However, I cannot make any application see them. When I configure the soundcard, it shows recording level slider places for them, and for other alleged input possibilities on the computer, but it allows no level adjustment for them individually (no actual control "knob" appears on the slider track), as if they simply are not available to the soundcard itself.

There is a master recording volume/gain/level/whatever that is functional when using the single stereo Line In jack on the back of the damn thing, but I can't get L/R component audio to be recognized by the front panel line ins. Yes, I have tested the audio source, and that isn't the problem. It is simply as though those front panel inputs are not being picked up by the sound card or its drivers.

Ideas? I have updated the soundcard drivers, BTW.