Long Islanders who are fully vaccinated are expressing their frustration Monday over trouble trying to get the state's Excelsior Pass app to work.

The trouble with the app comes as the Islanders get set to take the ice at Nassau Coliseum Thursday where fans will be sitting in sections divided by who is vaccinated and who is not.

Emma Nacewicz has been fully vaccinated for about a month but she still can't prove it using the state's Excelsior Pass phone app.

"I went online, signed up and it came up with an error message," says Nacewicz.

The same thing happened to David Horowitz, an Islanders fan who plans to be at the playoff game Thursday.

"When I enter my information it tells me, 'We can't verify your information,'" says Horowitz.

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Their experiences are just two examples of technical glitches that have been plaguing the app. The pass is being touted by the governor as a way to safely pack people inside arenas and other venues once again.

New York Knicks owner James Dolan said vaccinated fans will get priority during the upcoming playoffs.

"We're going to still make room for people who are unvaccinated," says Dolan. "But honestly, we're going to favor the vaccinated."

Rep. Lee Zeldin, who's running for governor, says the positivity rate is low enough to start fully reopening large arenas without testing or proof of vaccination. He says the Excelsior Pass could present a problem when it comes to privacy.

"The big question mark is which businesses and others will be seeking to utilize the Excelsior Pass," says Zeldin. "This is a slippery slope. I don't believe that we should start going down this road at all." 

Cuomo hasn't commented on Zeldin's criticism of the pass, but state officials say the majority of users have had a seamless experience.

Anyone having trouble with the app should make sure they are entering the information exactly as it's written on the vaccination card or it will lead to an error.