Student volunteers help at a booth to encourage on-campus voting for students during a Vote for Our Lives event at the University of Central Florida in Orlando on Oct. 31. (John Raoux/AP)

Ronni Isenberg was away at college when one of her former neighbors stormed into Marjory Stoneman Douglas High School last year and killed 17 people, including one of her friends.

As she watched the aftermath of the tragedy unfold from Syracuse University in New York, feeling too far away from home, Isenberg immediately knew she had to join other Parkland, Fla., students in channeling her anger into political support for tougher gun laws.

Last March, a month after the shooting, Isenberg flew from college to Washington to participate in the March for Our Lives demonstration on the Mall, organized by Parkland students. She made sure she was registered to vote in Florida and then encouraged her friends at Syracuse to also register.

But Isenberg recently learned that her vote — as well as those of dozens of students from Parkland — was probably never counted.

About 1 in 7 mail-in ballots submitted by college-age voters in Parkland were rejected or failed to arrive in time to be counted, according to an analysis. The findings are adding to questions about the reliability and fairness of the Florida electoral system, including its ballot signature requirement that became a flash point in the November recount between U.S. Sen Rick Scott (R) and the Democrat he ousted from office, Bill Nelson.

“We wanted to make a change and vote for change,” Isenberg said. “I should have had the right to vote, and my vote should have been counted.”

The problem with Isenberg’s ballot was discovered by Daniel A. Smith, chairman of the political science department at the University of Florida who analyzed Florida’s open-source voting file. A veteran researcher of Florida elections, Smith said that 15 percent of mail-in ballots submitted by Parkland residents between ages 18 and 21 were never counted in the midterm election, far exceeding the statewide average.

Among all Floridians between 18 and 21, about 5.4 percent of mail-in ballots were rejected or uncounted, Smith said. The statewide average of rejected or uncounted mail-in ballots for all ages was 1.2 percent, Smith noted.

“If you are voting in Florida, and you are young in Florida, you have a good chance of your ballot not being accepted,” Smith said. “Imagine going to the ATM, and every 10 times you go, instead of spitting out your money, they take it or they lose it.”

A spokesman for the Broward County Supervisor of Elections said he could not comment on Smith’s findings “unless and until” the office reviewed his data and methodology.

But the office found a countywide rejection rate within the 18-to-21 age range that was “half” of the 10 percent that Smith discovered. Among all mail-in ballots cast in Broward County regardless of age, 5,464 ballots were not counted — a rejection rate of 2.8 percent, the election office said.

More than half of those ballots, 3,458, were not accepted because they arrived after Election Day and could not be legally counted. Others were not signed, contained a mismatched signature, were signed by someone other than the voter, or returned to the election office as “undeliverable,” according to country records.

Under Florida law, election officials must compare the signature on an absentee ballot to the signature on the voter’s registration form.

If the signatures do not match, the voter can file an affidavit, along with proof of identify, to try to rectify the problem. But the Vote-by-Mail Ballot Cure must be received at the election office by 5 p.m. on the day of the election.

In a report issued in September and written by Smith, the American Civil Liberties Union concluded that Florida’s vote-by-mail system disenfranchises younger voters as well as racial and ethnic minorities.

During the 2016 election, the report stated, people under 30 made up just 9 percent of all vote-by-mail participants but accounted for about 31 percent of all rejected ballots. Black voters made up 9 percent of the vote-by-mail participants but accounted for 17 percent of rejected ballots, the report concluded.

In November, as the nail-biter election between Scott and Nelson went to a recount, there was a flurry of lawsuits challenging Florida voter laws.

One lawsuit noted that Florida election officials had rejected more than 4,000 ballots for mismatched signatures. And under existing law, those challenged signatures needed to be rectified by 5 p.m. on Election Day, even though state law gave voters until 7 p.m. for their mail-in ballot to arrive at local election offices. (There is an exception for overseas and military ballots, which are accepted up until 10 days after the election).

Siding with the plaintiffs, a federal judge ruled that the state’s signature-match standards were unconstitutional. The judge gave Florida voters a 10-day extension to fix their signatures. Last month, the U.S. Court of Appeals for the 11th Circuit upheld that lower-court ruling.

Myrna Pérez, a voting rights lawyer with New York University Law School’s Brennan Center for Justice, said more public education is needed to better inform voters about mail-in-ballot deadlines, especially those voting for the first time. But Pérez said she isn’t sure major changes are needed to the state’s signature requirement, saying such laws help prevent legislators from enacting even more onerous conditions.

“We don’t want people to demand strict voter ID instead of a signature,” Pérez said.

In Parkland, Smith suspects, many students preregister to vote in high school before their 18th birthday. As they age into young adults, he added, their signatures evolve.

“Many of those students go off to college, develop a new identity, including some more sophisticated signatures,” Smith said. “Their new signature may not look anything like it did in high school civics class.”

About 250 Parkland residents ages 18 to 21 registered to vote between February 2018, when the Stoneman Douglas High School shooting took place, and Election Day. More than half of them voted, an unusually strong turnout among young voters in a midterm election, Smith noted.

Many of the Parkland young adults whose ballots were rejected say state and local election offices are to blame.

Luciany Capra, a 19-year-old student at Mount Holyoke College in Massachusetts, said she requested her absentee ballot at least a month before the election. It still had not arrived weeks later, and for two consecutive days, no one answered the phone at the Broward County election office, Capra said.

She said she finally got through the Friday before the election. After being placed on hold for an hour, “They were like, ‘Oh, you should have gotten it.’ But I never got it,” Capra said.

The election office mailed it again, and she received it on Election Day.

Capra filled out the ballot, voting for mostly Democratic candidates. She mailed it back, even though she doubted it would arrive in time to be counted.

Then, a few days after the election, Capra said somebody called her and told her that her ballot had been rejected because her signature did not match and that a judge had granted her more time to re-sign her ballot.

“I submitted the request for it to be counted and signed a whole bunch of papers, and then I never heard back from anyone,” said Capra, a sophomore who was voting in her first election. “If there was any mistake, it was a mistake on their end.”

The Broward County election office said that for years it has expressed concern about how slowly the post office has delivered ballots and other correspondence to voters. It noted that all mail from Broward County is first sent to a processing center in Miami-Dade County.

But Reagan Edgren, 19, said she doesn’t think the problem with her ballot rests with the Postal Service. She said the Broward election board was too overwhelmed to diligently account for all the mail-in ballots.

Election board records examined by Smith show that Edgren, a student at American University in Washington, D.C., requested her mail-in ballot Oct. 27. The records show the election board mailed it to her Oct. 30 and didn’t receive it back until Nov. 17, nearly two weeks after the election.

Edgren is certain she mailed it before Election Day.

“They kept telling us that voting is going to be the way we can make a change,” Edgren said. “But when they don’t allow our votes to be counted, they are essentially saying we don’t get a voice.”