Code working in pycharm but throwing error in codeacademy page. Any help appreciated.

Python 9/7

Getting this type of error messages

Oops, try again. grades_variance([3, 2, 2, 3, 1, 2]) returned None instead of the expected: 0.4722222222

In pycharm I am getting this result

/usr/local/bin/python /Users/xxxx/Documents/python/python/average_variance1.py

0.47222222222222215

Process finished with exit code 0

```
grades = [100, 100, 90, 40, 80, 100, 85, 70, 90, 65, 90, 85, 50.5]
def print_grades(grades):
for grade in grades:
print(grade)
def grades_sum(grades):
total = 0
for grade in grades:
total += grade
return total
def grades_average(grades):
sum_of_grades = grades_sum(grades)
average = sum_of_grades / float(len(grades))
return average
def grades_variance(scores):
average = grades_average(scores)
variance = 0
for score in scores:
variance += (average - score) ** 2
result = variance / float(len(scores))
print(result)
```