I see that I've answer this for you in the audio section but you choose to ignore it.
I was having your exact problem with adobe audition. it a pain in the arse to configure to record from the line in. cool edit (the original adobe audition) pro was easy to do, but audacity is by far the easiest. it's free, plus there are a million tutorial floating around the net on it, even though you won't need one
now you can ignore my advice and keep having the problem or wait forever for an answer or you can do what I said