I'm sorry... the Fritzing files I uploaded were wrong. They didn't correspond to the wiring I had done.
That incorrect version had a black wire going from GND on the breadboard to 5V on the Arduino and nothing going from the power row to the Arduino.
This new version has the correct, in that it corresponds to what I've done, wiring.
MQ-2 Breadboard.fzz (3.31 KB)