Three years after helping render punch-card voting systems obsolete, Broward County voters have proven that no election system is foolproof. In Tuesday's special election to fill state House seat 91, 134 Broward voters managed to use the 2-year-old touch-screen equipment without casting votes for any candidate. How so many happened to cast nonvotes remains a riddle. Unlike with punch cards or paper ballots, there's no paper record with electronic voting that might offer a clue to the voter's intent.