London, March 20 (IANS) Hollywood actress Kristen Stewart who took up the offer to play Joan Jett in 'The Runaways' had to face difficulty during singing in the movie.

The 19-year-old actress knew she wanted the role of rocker Joan in the movie, but had problems with the singing aspect of the film, reported contactmusic.com

'I said that I wanted to do it as soon as someone said, 'There's a Joan Jett movie, and they want you to play her.'

'The most difficult thing was the performances, because I'm not a performer. The singing stuff, you learn so much about yourself. I don't know how to be more specific about it,' she said.