It is a strange thing. I have like 10 different accounts with Amazon. All accounts can write product reviews fine but when I vote on a review: "Was this review helpful? Yes/No" Only one of my vote counts. It doesn't matter how many times I vote with all my other accounts. I've tried using different IP address (hide-my-ip), anonym.to and incognito chrome browser. Amazon seems to know that I am voting twice and they are not counting my vote. Any advice? Thanks!