Singer suffered a suspected chest infection yesterday (October 26)
Usher and Mariah Carey are also set to appear on the new album
Burlesque celeb hopes to help the singer
Sources say she has no finished songs
See what the singers look like in plastic format
Singer will spin tunes in Camden on Thursday (Sept 11)
Grace Jones, Hot Chip and The Specials also play the rain-lashed bash
Rob da Bank reveals he's prepared for a no-show
Duffy, Iron Maiden, Madonna - your music gossip stop
French festival promoter fury at missed show