By Dana Kozlov

(CBS) – Voters said “yes,” and Hinsdale-Clarendon Hills school officials were ready to go ahead with a new middle school.

Then five people put the brakes on the plan.

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CBS 2’s Dana Kozlov reports.

The superintendent of School district 181 walks through the 41-year-old Hinsdale Middle School he says needs to be torn down and rebuilt.

“It is mission-critical,” Don White says.

And in November, 54 percent of voters said yes to a referendum funding the new school, which would be built around the existing structure. That would then be replaced with a parking deck.  The project’s green light turned a sudden red when five people slapped the district with a lawsuit.

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The why is unusual. The lawsuit states DuPage County was supposed to notify the public of the referendum no earlier than Oct. 11. But the notice went out three days early. That, says the plaintiffs’ lawyer by phone, is illegal.

“It wasn’t us that created this,” attorney Clint Krislov says.

Residents in favor of the new school says that lawsuit is now costing taxpayers more money.

Both sides will be in court Monday, for a motion to dismiss the lawsuit.

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The new school is projected to cost taxpayers $53 million.