South Carolina voter suppression

OK, sorry for the bad joke in the headline, but South Carolina Governor Mark Sanford was turned away from the polls because he forgot his voter registration card:

A sheepish Gov. Mark Sanford was turned away from a South Carolina polling place Tuesday because he forgot his voter registration card.

The casting of ballots in front of the news media is a well-worn tradition for politicians, but it was no Kodak moment when Sanford discovered he had left his card behind.

[..]

Eventually, the poll manager at Sullivan's Island Elementary School politely told the governor that he couldn't vote unless he had a registration card, and the Sanfords departed.

Later, Sanford told reporters that his card was in the capital, Columbia, but he planned to obtain a replacement immediately so he could cast a ballot.

Maybe I'm mistaken, but I thought that the Help America Vote Act (federal law) allowed for a provisional ballot to be cast in situations like this? They are in Tennessee. (In Tennessee you don't even have to cast a provisional ballot -- several forms of ID are accepted as long as your name is on the registered voter printout at the polls.) Is it possible that neither the governor nor the election worker at the polling place are aware of the law, or am I missing something?