As I said somewhere (can't remember where), a lot of provisional ballots don't get counted. From the Rolling Stone article...

'In 2004, an estimated 3 million voters who showed up at the polls were refused regular ballots because their registration was challenged on a technicality. Instead, these voters were handed "provisional" ballots, a fail-safe measure mandated by HAVA to enable officials to review disputed votes. But for many officials, resolving disputes means tossing ballots in the trash. In 2004, a third of all provisional ballots — as many as 1 million votes — were simply thrown away at the discretion of election officials.'