Can't get all followers, just half or a little more

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Hi
I have a question about you instabot.py , I am using it to get followers of specific accounts.
but for example , a random account which I've just tested is "art.ali" . This account has 34 followers but in the csv file . Code records only 16 accounts :(
I added a few lines to save them in the txt file but it's just recording 25 accounts, and still I could not get all 34 accounts, I tested this for an account with 38 followers again and it got 21 accounts.
How can I get all the followers' usernames? or all following usernames?