Whitney Houston was scheduled to perform at London's Fashion Rocks event but pulled out at the last minute over health worries. The 44-year-old star appeared on stage at the Royal Albert Hall last Thursday (18Oct07) to introduce British girl group Sugababes, but she had initially planned to join the band for their rendition of Lady Marmalade. Houston hopes to revive her singing career after several highly publicised stays in rehab, but called off her comeback performance citing poor health. A source tells British newspaper The Independent, "Whitney rehearsed that morning but pulled out, complaining of a sore throat. She had to be replaced by Patti LaBelle."