Setting up a vote reporting view

I'm trying to set up a view to list nodes by vote count (i.e., to answer the question, which node got the most votes). However, it appears that I only ever have one vote per node. Each time I vote, it simply updates any existing vote for that node. Which means that there is never more than one vote per node.

I've set up the Voting API to allow votes to counted immediately. Have I missed something in the configuration? I know this isn't just something in Views, because I can see the behavior in the votingapi_vote table.

Thanks