PARK CITY, Utah (AP) – Forget hitting the ski slopes, grabbing bags of swag, or long, luxurious nights by the fire. Joan Rivers is working the Sundance Film Festival.

"It is so frustrating to be at Sundance because you can't see anything but your own movie," said Rivers, who attended the festival in support of the documentary 'Joan Rivers: A Piece of Work', directed by Ricki Stern and Annie Sundberg. The film premiered on Monday night.

"Everybody's saying, `Did you see this? Did you see this?"' the 76-year-old comedian said. "You go, `No! No! No!"'

The film offers both a seriously funny and just-plain-serious look at Rivers. Rivers joked about promoting the documentary. "I really hate it," she said. "I can't get to the gifting booths. We barely made our way into one of them. And there was nothing left but extra-larges. So, I'm very bitter about Sundance, if you want the truth."

But, she added: "Of course, it's a great honour."

Rivers said she had no influence on the content of the documentary. "Once they said, `Let's do it',' it was their's to do," she said. However, she did grant the filmmakers access to her life.

"You're going to do a documentary, you've got to have access," she said.