If you’re using a Humble Pi #raspberrypi breakout board and controlling the GPIOs via the RPi.GPIO module, the labels on the board correspond to the BCM pin numbers, not the BOARD numbers. Your setup call should look like GPIO.setmode(GPIO.BCM), then calling

GPIO.setup(4, GPIO.IN)
GPIO.output(4, True)

will raise the level of the pin marked G04 on the Humble Pi board.

See also: RPi.GPIO Basics — Setting Up, Numbering Systems