Headset still not working, please help

[Guest]

First off, the problem is that I can hear out of the mic but I cannot be
heard through the microphone. I have a custom built computer with Windows XP
Home. I believe I ahve a C-Media AC97 Audio Device for a sound card. I
checked that the headset was plugged into the right ports. Also, I tried the
test hardware in the Sound, and audio devices section and it could not detect
my voice at all. My mic is not muted nor is it at a low volume. Please help!

 

[Guest]

Forgot to add that I tested the microphone on my sibling's computer and it
worked fine, so the mic isn't faulty.