Quantum Tiny Linux - GPIO-KEY not working

Products & Technology
1

I want to use the GPIO-KEY button in my small project, the button is connected to pin 18. The button is not responding, I am using the RPi_GPIO library in Python. The program looks like this:

import time
import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BOARD)
GPIO.setup(18,GPIO.IN)

while True:
    if GPIO.input(18) == 1:
        print("YES")
    else:
        print("NO")

What am I doing wrong ?