Strange problem - need unused variable to make (Blink like) sketch run

Projects Programming
6 
int led = 7;         //  This assigns the value 7 to a variable called led
void setup() {                
  led++;                //  This increments led, making it have a value of 8
  for ( int i=7;i<14;i++){      // these two lines set pins 7 - 13 to OUTPUT
    pinMode(i, OUTPUT);
  }
}

void loop() {
  for ( int i=7;i<14;i++){
    digitalWrite(i, HIGH);  // This line sets pins 7 - 13 HIGH, 1 pin per loop
    delay(100);
    digitalWrite(i, LOW);  // This line sets pins 7 - 13 LOW, 1 pin per loop
    delay(100);
  }
} // and this line makes it go all around the loop, setting pins 7 - 13 HIGH/LOW in turn

You need to use the variable led in your digitalWrite(). Just because you called it led, doesn't make it automatically know what to do.