Invisible Ink on Ballots?

Some votes were apparently lost, however, when about 20 folks at a Chicago precinct were given styluses designed for touch-screen machines instead of ink pens. When voters complained the devices made no marks on their paper ballots, a ballot judge told them the markers were full of invisible ink.

"After 20 people experienced the same problem, somebody said 'Wait,
we've got 20 ballots where nobody's voted for anything,'" said Board of
Elections spokesman Jim Allen. Officials were trying to contact the
voters; Allen said the both the voters and the judge believed the
invisible ink theory.