I my line-in port broke or am I doing it wrong?

Hi all,

I've recently bought a headset so i can talk to a friend over steam without having to do the whole 'press a button to talk' thing. However i can't get the headset mic to work.

I tried to deduce if it was the port or the mic by plugging in my electric guitar to garage band (as i had no other mic to plug in, or anything else to plug the mic into) and that worked fine. Had a little jam and mess around with the customisable software amps and stuff for a while even. So anyway, i replaced the headset today thinking it must have been the mic, and the new set is exactly the same. Can hear through the speakers, and yet the mic isn't picking up anything.

Am I missing something?

I have been going into sounds in System Preferences and changing the input from built in mic to the line in, and then checking to see if its picking anything up, but i doesn't. All it picks up is the slight distortion when i plug in or unplug the mic.

Any input at all would be useful as I really don't want to have to take this MBP in for repairs again. Its already a replacement for my last one after apple swapped it due to the last one having to get repaired so many times...

Edit: And yeah, that is supposed to say 'Is my line-in port broke...' for the title, just noticed as I posted

 

in game. If i don't set it up so i press a button to talk without a headset then obviously everyone listening over the com is gonna hear not just when i talk, but game music, background music, people in the room, etc. With a headset it will just pick up my voice, or at least i can set it like that easier.