Recording Is Not Working!
You can play audio, but you can't record anything!!!  There can be many reasons why this is not working. 

1. If recording from the microphone, make sure your microphone is plugged in to the right input in the back of your sound card.  Consult your sound card's documentation.  Or, if you are recording from the Line-In, make sure that the you are connected to the Line-In port in the back of your sound card.
2. You're trying to record audio from a CD but you are not seeing any signal.  Make sure that your sound card has a connection to your CD player.  This is usually an internal cable.  Most new computers do not have this problem, though.
3. Make sure that you are arming the correct input.  See more on arming tracks.
4. Make sure that you have the correct source selected for the armed track.
5. Make sure that the armed track's recording level is turned up.  See more on setting the level.
6. Try recording in Wave mode if you are in ASIO mode or vice versa.  You can try WaveRT mode if you are using Vista.

Always make sure that you have the latest drivers for your sound card.  Visit your sound card manufacturer's website to see if there is an update.