Singer Sevyn Streeter was ecstatic about the opportunity to sing at the 76ers home game against the Oklahoma City Thunder on Wednesday night.
She urged fans on Twitter before the game to come see her perform.
But she ended up not performing at all, after she was told her outfit was inappropriate by the 76ers organization.
"I'm at the 76ers game to sing the national anthem," the 30-year-old singer says in a video which has since been retweeted more than 13,000 times.
"The org is telling me that I can't, because I'm wearing a 'We Matter' shirt," she said.
The video ends with the reaction of someone off-camera: "Whaaaaat?"