Even the last - failed on extra 11

def checkio(array):

leng = len(array)
result = 0
if leng == 0:
    return (0)
else:
    for item in array:
        if array.index(item) % 2 == 0 and not item == 0:
            result +=  item
    return (result * (array[leng-1]))

This is my code. The weird thing is that it works for every test apart from the last one (Extra 11) where it gives me quite a lot of negative numbers and positive numbers. My answer is 500 away from what it is supposed to be. I don't see why my code should fail on this one but work on all the others. Even the ones with negative numbers. If someone could help me I'd be very grateful.