An optical scan vote tallying system, now used by some 300 U.S. municipalities, misreported the results of a Palm Beach County, Florida, municipal election last month.

Dominion Voting Inc.'s Sequoia Voting Systems device mistakenly awarded two Wellington Village Council seats to candidates who were found in a post-election audit to have lost their races.

The results were officially changed last weekend after a court-sanctioned public hand count of the votes.

Palm Beach County supervisor of elections Susan Bucher did not immediately respond to a request for comment on the problem.

According to a story in the Palm Beach Sun Sentinel , the Sequoia vote counting software was set up in a way that didn't correspond to the Wellington County ballot distributed to voters.

As a result, votes meant for one candidate were credited to a different candidate.

"Election-night totals on Wellington's three races were shifted in a circle -- with village council Seat 4 votes going to the mayor's race, votes for mayor going to council Seat 1, and votes for Seat 1 going to Seat 4," the Sentinel story said.

In a product advisory notice issued last Friday, Dominion warned customers that problems could arise if the contest order on a paper ballot does not match the ballot order programmed into Sequoia machine.

"The contest order on the ballots in the database can become out of sync with the contest order shown on the corresponding paper ballots," the company noted.

If the issue is not identified during pre-election tests, "election results will show the correct number of votes, but assigns them to the wrong candidate" the company said in the advisory.

In a statement posted on the Palm Beach County Election Supervisor's site, Bucher blamed Dominion for not alerting election officials about the potential problem.

"We were not made aware of the software shortcoming," Bucher said.

She cited a statement issued after the election by a Waldeep Singh, vice president of customer relations at Dominion, which blamed the problem on "a mismatch between the software which generates the paper ballots and the central tally system.

"This synchronization difficulty is a shortcoming of the version of software currently being used in Palm Beach County and that shortcoming has been addressed in a subsequent version of the software," the statement said.

In a later letter sent to Florida Secretary of State Ken Detzner, Dominion president John Poulos appeared to backpedal from Singh's statement.

Poulos maintained that the company's software had functioned precisely as designed and contended that the precise reason for the mismatch remains unknown.

Blogger Brad Friedman, who maintains a blog chronicling election issues, said the incident should serve as a warning to the 285 jurisdictions around the country using the Sequoia/Dominion system today.

While the hand count settled Wellington council elections, "it hasn't settled all question about what went wrong, and whether voters in the states which currently use the faulty Dominion/Sequoia system --- many of them swing states --- should rely on the results reported by it," he wrote.

The incident in Palm Beach County highlights the importance of post-election audits, said Dan McCrea, president of Florida Voters Foundation, an election watchdog group.

"The most effective way to mitigate such machine errors is to perform statistically significant post-election audits that take place before elections are certified," McCrea said.

If the Wellington results had been certified, there would have been no recourse under Florida law to change the results later, he said. "Everyone might have stood in a circle and agreed it was incorrect. But legally there would not have been a way to stand down the results," McCrea said.

Florida election law does not allow for manual recounts unless a court orders it, which is what happened in Wellington Village, he added.

McCrea noted that companies such as Dominion have to do a much better job of minimizing the potential for errors. He noted that e-voting companies are under tremendous cost pressures and may not always be able to deliver required security, he said.

"We need to consider whether it is a viable market for private companies or whether in fact it requires a hybrid public-private effort," he said.

Pamela Smith, the president of election watchdog group Verified Voting said the Wellington Village incident also highlights the need for election officials to do better pre-election logic and accuracy tests.

In this case, it's not clear whether such testing would have revealed the issue that resulted in the erroneous reporting, she said. But in many instances, such tests are not done in a robust manner, she said.

The U.S. Election Assistance Commission is currently funding several pilot projects designed to help develop better develop pre-election Logic & Accuracy and post-election audits Smith said.

Several jurisdictions from states such as California, Colorado and Connecticut are participating in the effort, she noted.

States such as Florida, which have a very small election result-certification window, should also consider giving election officials more time to conduct robust post election audits, she said.

Dominion did not respond to a request for comment.

Jaikumar Vijayan covers data security and privacy issues, financial services security and e-voting for Computerworld. Follow Jaikumar on Twitter at @jaivijayan, or subscribe to Jaikumar's RSS feed . His e-mail address is jvijayan@computerworld.com.