Believe singer Cher has revealed that her collaboration with Lady Gaga may not be released.

When Cher was asked by a fan on her Twitter page why The Greatest Thing hasn't been aired yet, the 67-year-old singer explained that Gaga wasn't impressed with the song.

Cher wrote: ''It's done & she [Gaga] doesn't like it, or want it to come out. She's an artist, it's up to her. I'm disappointed 2 (sic).''

Cher is set to release her 26th studio album, Closer To The Truth, in September.