Why is this not a valid solution for Index Power?

Could someone explain to me, why this is not a valid solution? The exercise:

You are given an array with positive numbers and a number N. You should find the N-th power of the element in the array with the index N. If N is outside of the array, then return -1. Don't forget that the first element has the index 0.

Let's look at a few examples: - array = [1, 2, 3, 4] and N = 2, then the result is 32 == 9; - array = [1, 2, 3] and N = 3, but N is outside of the array, so the result is -1.

Input: Two arguments. An array as a list of integers and a number as a integer.

Output: The result as an integer.

The code:

result = -1
    try:
        result = array[n] ** n
    except IndexError:
        result = -1
    return result

I did run the text examples, and all of them was fine so why is this not accepted?