Election judges at a Far North Side Chicago precinct told 20 voters that a non-working voting pen contained "invisible ink."

It's invisible ink, officials said. The scanner will count it.

But their votes weren't recorded after all.

"Part of me was thinking it does sound stupid enough to be true," said Amy Carlton, who had serious doubts but went ahead and voted anyway.

As it turns out, Carlton was one of 20 voters at the precinct who were given the wrong pen to use. They were also then told, apparently by a misinformed judge, that the pens have invisible ink, elections officials said.

As a result, the votes were not counted. But officials insisted there were no dirty tricks involved.