The sensitive Diebold TS touch screen registered U.S. Senator Mikulski's vote incorrectly during a demonstration at a local festival.*

But as Mikulski voted on a mock referendum question, her hand inadvertently grazed the screen and cast a "yes" vote for another mock question, according to Morrill, who stood next to her as she tested the machine.

Mikulski, who had planned to vote "no" on the question, tried to push the "no" button to change her vote, but the machine didn't make the change. She eventually was able to correct the ballot.

[Mikulski's aide Michael Morrill] said ... the example reinforces her belief that a voter moving quickly through a ballot could inadvertently cast the wrong vote.