Microphone doesn't work

I got a new dual 2.0 g5 and its working great.

The only trouble i have currently is that there doesn't seem to be any way to get a microphone to work with the machine.

I checked everywhere if the line in is maybe muted but nothing seems to be wrong. I tryed several different mics on the g5 and none worked at all.
When i'm in preferences -> Sound -> Input i cannot get the bars to fill up even if i shrike in the mic.
😱


Am i missing something obvious or is my line in broken ?

I just tryed it in skype just to make sure but sure enough, my partner can't hear me.

😕