It works for me from my kindle, but I'm a little concerned that I was allowed to vote twice.
It says in the small print next to "Cast Your Vote" that you can select two choices.
Like voting for more than one tortoise in the Calendar Contest, I guess.
Are you sure it didnt just change your vote(s)? I've voted multiple times but it is only re-allocating the votes, not increasing the total other than for the initial vote, and only 2 options may be selected. Changing from voting for 2 to just one also decreases the total votes.