Nyquist error.

The exact steps I followed:

1: Install audacity 2.0.6
2: record about a second of sound from microphone in mono
3: effects>vocoder with default settings
4: “nyquist did not return audio”.

I have done literally nothing except install the program and the default functionality breaks. Exactly what happened and how do I fix it?

Vocoder requires stereo input (and left and right channels not to be split to separate tracks), as it says in the Manual: http://manual.audacityteam.org/o/man/vocoder.html.