Josee Stetich and her friends from Bountiful High School were dressed up and ready to go.
The three didn't have dates, so they decided to go together.
Two of them bought a ticket together and were allowed to get in. But Josee, who was there alone, wasn't. Officials say it was a "couples-only affair." All three girls left.
"I've gone to this school for three years, and I never even knew about that rule," Josee said. "They said, 'no you can't come in, because you don't have a date.' "All my friends are upset. My mom's upset."
The girls say the evening wasn't a total loss. They went on a tour of a local chocolate shop and had a blast.
Still, the girls and their parents say they'll be demanding a change in school policy.