nothing records using built in input

Have Mavericks 10.9.2 and Audacity 2.0.5 Cannot get any recording using built in input for sound playing on the computer. No external devices are beijg used. Have checked settings in Audicity and seems there are no problems. All that happens is flat line during recordings. Have not had this problem before upgrade to Mavericks. Any suggestions?

Macs don’t natively record sound playing on the computer. To get that you have to install a third party software program such as SoundFlower.