Cant Record Sound

I got a new computer with a great motherboard. i can record my games sound with fraps perfect. but i cant record desktop sound with hypercam or Camtasia Studio
Answer #1
Try right clicking the volume controller and click “recording devices”. Select “Stereo Mix”, click properties, then at the bottom under “device usage” choose “use this device”. Make sure you disable all the other recording devices also.
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Answer #2
this is all i got

it says line in is unplugged but how do i use it? there is no plug for line in? my motherboard is a expensive gaming motherboard. it has sound i know it because fraps records perfect sound. also has like 8 ports in the motherboard to plug audio wise things in.
Answer #3
Any Ideas