How to make the level variable match with the random number?

I try to run this program but the output of level is same not match with a random number. I think I get wrong when I code the variable of level. I have tried so many time but I still can not solve it.

This is for random number

    ArrayList<Hero> listHeros = new ArrayList<Hero>();
    //ability using random number
    int minimum = 0;
    int maximum = 99;
    int range = maximum-minimum+1;
    Random random = new Random();
    int randomNumber = random.nextInt(range)+minimum;

This is for if-else. The level must match whit a random number

    String level;
    if (randomNumber >= 90){
      level = "S";
    }else if(randomNumber >= 80){
      level = "A";
    }else if(randomNumber >= 60 ){
      level = "B";
    }else if(randomNumber >= 40){
      level = "C";
    }else{
      level = "Fail";
    }

This is Herro list

    listHeros.add(new Hero("Saitama", random.nextInt(range)+minimum, level));
    listHeros.add(new Hero("Genos ", random.nextInt(range)+minimum, level));