I think what Pete is saying, and I could be wrong here, is that if you have voted, it counts toward the 50% they need no matter how you voted. Only the people who did not vote,and will not vote,can affect the outcome.
If your shares were already voted it is best to leave them NO. from what I was told by proxy vote hotline was an abstain vote doesn't count as for or against BUT YOUR SHARES ARE REPESENTED IN THE VOTE. I am leaving my NO vote stand. IF YOU HAVE NOT VOTED AND ARE AGAINST THE MERGER AND/OR IT'S TERMS IT IS BEST TO NOT VOTE AT ALL.