Arduino Project Sensor MQ7 with LED indicator

Other Hardware Sensors
3

I use this sketch but when I try, in serial monitor arduino IDE nothing value number.
Whats Wrong?

const int analogPin = 0; // the pin that the potentiometer is attached to
const int ledCount = 10; // the number of LEDs in the bar graph

int ledPins[] = {
10,9,8,7,6,5,4,3,2,1 // Here we have the number of LEDs to use in the BarGraph
};

void setup() {

for (int thisLed = 0; thisLed < ledCount; thisLed++) {
pinMode(ledPins[thisLed], OUTPUT);
}}

void loop() {
//This is the code to light up LED's
int sensorReading = analogRead(analogPin);

int ledLevel = map(sensorReading, 500, 1023, 0, ledCount);

for (int thisLed = 0; thisLed < ledCount; thisLed++) {

if (thisLed < ledLevel) {
digitalWrite(ledPins[thisLed], HIGH);
}

else {
digitalWrite(ledPins[thisLed], LOW);
}
}
}