Cannot record keyboard on Ubuntu 16.04

[asravan]

I am using Audacity on Ubuntu 16.04 to record from an electric piano through an input jack. My laptop recognized the recording device and I can see input levels fluctuating when I play from my keyboard (although I can't hear anything). The device toolbar in audacity is empty. When I hit the record button it gives the following message:
"Error opening sound device. Try changing the audio host, recording device and the project sample rate"

I've already tried re-installing my sound drivers. Does anyone know what's going on?

[Luc]

Look for an icon that looks like a microphone. On my copy of Audacity, it's present in three places. One of them is right next to a drop-down box where you select the audio input. Give it a try.