If condition does not work with me why ? even the logic is true

This is my code of merging 2 sample files. the code running will but if conditions read (not exist file) which is not logic (-if- the file does not exist go to -else if- if not go to -else-) but it does not work like that

can you know why if condition reads not exist file?

my_list = range(0,5)
Number = 0
for i in my_list:
    print(Number)
    print(i)
    if os.path.isfile('C:/Users/sample{}.wav'.format(i)):
        print ("File exist")
        sound1 = AudioSegment.from_file(
            "C:/Users/sample{}.wav".format(i))
        sound2 = AudioSegment.from_file(
            "C:/Users/s/sample{}.wav".format(i))
        combined = sound1.overlay(sound2)
        combined.export("C:/Users/mixing{}.wav".format(Number))
        Number = Number+1
        print("if")

    elif os.path.isfile('C:/Users/s/sample{}.wav'.format(i)):
        print ("File exist")
        sound1 = AudioSegment.from_file(
            "C:/Users/sample{}.wav".format(i))
        sound2 = AudioSegment.from_file(
            "C:/Users/s/sample{}.wav".format(i))
        combined = sound1.overlay(sound2)
        combined.export("C:/Users/mixing{}.wav".format(Number))
        Number = Number+1
        print("else if")

    else:
        print("file Not exist")
        Number = Number-1
        print("index",i)
        print("NUMVER",Number)