Britney Spears' $15 million X Factor USA contract wasn't renewed because she was "very uncomfortable" on the show.
The show's boss Simon Cowell has admitted he didn't realise that the Scream & Shout singer is not a big talker and confirmed it was the main reason he decided to replace her on the judging panel this year after just one season.
The 55-year-old British star told The Ellen DeGeneres Show in a new interview that will air in the U.S. on Tuesday: "I didn't realise that! I kind of booked someone who couldn't talk, which is a bit of a problem when you want someone to judge."
He added: "She wasn't comfortable being negative, she didn't like it when the contestants spoke back to her, so she was just uncomfortable. I liked her. So we decided to change it this year and I thought I'll work with three girls because I like working with girls."
Simon also confessed that he only asked Britney, 31, to be a judge as he got caught up in competing with American Idol and The Voice USA to feature high profile judges such as Jennifer Lopez and Christina Aguilera.