Recording sounds on msn

I only just found out I could record any sound coming from my computer by holding down F2. So say I could record + send a clip of a song I was listening to in Media Player or FL Studio etc. This might not seem strange but I don’t have a microphone / webcam or anything.
So I had fun playing around with that but suddenly it stopped working and now everytime I try to do it I get a message saying:
Your Voice Clip was not sent because no sound was detected in the recording.
Any ideas? I’m doing nothing different than before.
Answer #1
BUMP!
Answer #2
Open your messenger window where you see your contacts, Click tools >> audio and video setup, Make sure all of them are turned up

Answer #3
Click the speaker in the bottom right hand corner of your taskbar, go to options > recording > tick stereo mix
Now try it