Line in/line out aux in problems

So ive got my aux out going into another computers line in (then into cooledit) then the line out from computer into 57sl aux in.

I couldnt get a signal in cooledit from the line in on the computer so switched to mic in (and selected mic from the sound and audio device console) then I recieved signals in cooledit. I tried to play it back through the 57 with the aux in turned up but nothing.

so why arnt i getting any line in response in cool edit and why arnt I hearing anything through aux in on the 57?

well it is a line in and not a mic in and you will damage the input on your laptop if u run the mic with a line. what are you trying to do .... record ?????